diff --git a/.golangci.yml b/.golangci.yml
index 393b17e6d2b2..4db9da06965c 100644
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -26,14 +26,6 @@ linters-settings:
             desc: use `github.com/jackc/pgx/v5` package instead
           - pkg: github.com/jackc/pgx/v4
             desc: use `github.com/jackc/pgx/v5` package instead
-      fjson:
-        # TODO https://github.com/FerretDB/FerretDB/issues/4157
-        files:
-          - $all
-          - "!**/internal/bson/*_test.go"
-          - "!**/internal/util/testutil/*.go"
-        deny:
-          - pkg: github.com/FerretDB/FerretDB/internal/types/fjson
       bson:
         files:
           - $all
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 38c6e5da529a..c6a12601a580 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -158,8 +158,6 @@ The `internal` subpackages contain most of the FerretDB code:
 
 - `types` package provides Go types matching BSON types that don't have built-in Go equivalents:
   we use `int32` for BSON's int32, but `types.ObjectID` for BSON's ObjectId.
-- `types/fjson` provides converters from/to FJSON for built-in and `types` types.
-  It is used for logging of BSON values and wire protocol messages.
 - `bson` package provides converters from/to BSON for built-in and `types` types.
 - `wire` package provides wire protocol implementation.
 - `clientconn` package provides client connection implementation.
diff --git a/internal/types/fjson/array.go b/internal/types/fjson/array.go
deleted file mode 100644
index d4300e9588e3..000000000000
--- a/internal/types/fjson/array.go
+++ /dev/null
@@ -1,61 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"bytes"
-
-	"github.com/FerretDB/FerretDB/internal/types"
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// arrayType represents BSON Array type.
-type arrayType types.Array
-
-// fjsontype implements fjsontype interface.
-func (a *arrayType) fjsontype() {}
-
-// MarshalJSON implements fjsontype interface.
-func (a *arrayType) MarshalJSON() ([]byte, error) {
-	var buf bytes.Buffer
-	buf.WriteByte('[')
-
-	ta := types.Array(*a)
-	l := ta.Len()
-	for i := 0; i < l; i++ {
-		if i != 0 {
-			buf.WriteByte(',')
-		}
-
-		el, err := ta.Get(i)
-		if err != nil {
-			return nil, lazyerrors.Error(err)
-		}
-		b, err := Marshal(el)
-		if err != nil {
-			return nil, lazyerrors.Error(err)
-		}
-
-		buf.Write(b)
-	}
-
-	buf.WriteByte(']')
-	return buf.Bytes(), nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*arrayType)(nil)
-)
diff --git a/internal/types/fjson/array_test.go b/internal/types/fjson/array_test.go
deleted file mode 100644
index c80572540c0a..000000000000
--- a/internal/types/fjson/array_test.go
+++ /dev/null
@@ -1,50 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"testing"
-	"time"
-
-	"github.com/FerretDB/FerretDB/internal/types"
-	"github.com/FerretDB/FerretDB/internal/util/must"
-)
-
-func convertArray(a *types.Array) *arrayType {
-	res := arrayType(*a)
-	return &res
-}
-
-var arrayTestCases = []testCase{{
-	name: "array_all",
-	v: convertArray(must.NotFail(types.NewArray(
-		must.NotFail(types.NewArray()),
-		types.Binary{Subtype: types.BinaryUser, B: []byte{0x42}},
-		true,
-		time.Date(2021, 7, 27, 9, 35, 42, 123000000, time.UTC).Local(),
-		must.NotFail(types.NewDocument()),
-		42.13,
-		int32(42),
-		int64(42),
-		"foo",
-		types.Null,
-	))),
-	j: `[[],{"$b":"Qg==","s":128},true,{"$d":1627378542123},{"$k":[]},{"$f":42.13},42,{"$l":"42"},"foo",null]`,
-}}
-
-func TestArray(t *testing.T) {
-	t.Parallel()
-	testJSON(t, arrayTestCases, func() fjsontype { return new(arrayType) })
-}
diff --git a/internal/types/fjson/binary.go b/internal/types/fjson/binary.go
deleted file mode 100644
index d5dee67f4480..000000000000
--- a/internal/types/fjson/binary.go
+++ /dev/null
@@ -1,51 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"encoding/json"
-
-	"github.com/FerretDB/FerretDB/internal/types"
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// binaryType represents BSON Binary data type.
-type binaryType types.Binary
-
-// fjsontype implements fjsontype interface.
-func (bin *binaryType) fjsontype() {}
-
-// binaryJSON is a JSON object representation of the binaryType.
-type binaryJSON struct {
-	B []byte `json:"$b"`
-	S byte   `json:"s"`
-}
-
-// MarshalJSON implements fjsontype interface.
-func (bin *binaryType) MarshalJSON() ([]byte, error) {
-	res, err := json.Marshal(binaryJSON{
-		B: bin.B,
-		S: byte(bin.Subtype),
-	})
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-	return res, nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*binaryType)(nil)
-)
diff --git a/internal/types/fjson/binary_test.go b/internal/types/fjson/binary_test.go
deleted file mode 100644
index 6bf80e11b2a2..000000000000
--- a/internal/types/fjson/binary_test.go
+++ /dev/null
@@ -1,49 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"testing"
-
-	"github.com/FerretDB/FerretDB/internal/types"
-)
-
-var binaryTestCases = []testCase{{
-	name: "foo",
-	v: &binaryType{
-		Subtype: types.BinaryUser,
-		B:       []byte("foo"),
-	},
-	j: `{"$b":"Zm9v","s":128}`,
-}, {
-	name: "empty",
-	v: &binaryType{
-		Subtype: types.BinaryGeneric,
-		B:       []byte{},
-	},
-	j: `{"$b":"","s":0}`,
-}, {
-	name: "invalid subtype",
-	v: &binaryType{
-		Subtype: 0xff,
-		B:       []byte{},
-	},
-	j: `{"$b":"","s":255}`,
-}}
-
-func TestBinary(t *testing.T) {
-	t.Parallel()
-	testJSON(t, binaryTestCases, func() fjsontype { return new(binaryType) })
-}
diff --git a/internal/types/fjson/bool.go b/internal/types/fjson/bool.go
deleted file mode 100644
index e22806151644..000000000000
--- a/internal/types/fjson/bool.go
+++ /dev/null
@@ -1,41 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"encoding/json"
-
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// boolType represents BSON Boolean type.
-type boolType bool
-
-// fjsontype implements fjsontype interface.
-func (b *boolType) fjsontype() {}
-
-// MarshalJSON implements fjsontype interface.
-func (b *boolType) MarshalJSON() ([]byte, error) {
-	res, err := json.Marshal(bool(*b))
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-	return res, nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*boolType)(nil)
-)
diff --git a/internal/types/fjson/bool_test.go b/internal/types/fjson/bool_test.go
deleted file mode 100644
index b4c894c44c0f..000000000000
--- a/internal/types/fjson/bool_test.go
+++ /dev/null
@@ -1,36 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"testing"
-
-	"github.com/AlekSi/pointer"
-)
-
-var boolTestCases = []testCase{{
-	name: "false",
-	v:    pointer.To(boolType(false)),
-	j:    `false`,
-}, {
-	name: "true",
-	v:    pointer.To(boolType(true)),
-	j:    `true`,
-}}
-
-func TestBool(t *testing.T) {
-	t.Parallel()
-	testJSON(t, boolTestCases, func() fjsontype { return new(boolType) })
-}
diff --git a/internal/types/fjson/datetime.go b/internal/types/fjson/datetime.go
deleted file mode 100644
index 9f9831b5e755..000000000000
--- a/internal/types/fjson/datetime.go
+++ /dev/null
@@ -1,54 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"encoding/json"
-	"time"
-
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// dateTimeType represents BSON UTC datetime type.
-type dateTimeType time.Time
-
-// fjsontype implements fjsontype interface.
-func (dt *dateTimeType) fjsontype() {}
-
-// String returns formatted time for debugging.
-func (dt *dateTimeType) String() string {
-	return time.Time(*dt).Format(time.RFC3339Nano)
-}
-
-// dateTimeJSON is a JSON object representation of the dateTimeType.
-type dateTimeJSON struct {
-	D int64 `json:"$d"`
-}
-
-// MarshalJSON implements fjsontype interface.
-func (dt *dateTimeType) MarshalJSON() ([]byte, error) {
-	res, err := json.Marshal(dateTimeJSON{
-		D: time.Time(*dt).UnixMilli(),
-	})
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-	return res, nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*dateTimeType)(nil)
-)
diff --git a/internal/types/fjson/datetime_test.go b/internal/types/fjson/datetime_test.go
deleted file mode 100644
index c0616f321821..000000000000
--- a/internal/types/fjson/datetime_test.go
+++ /dev/null
@@ -1,45 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"testing"
-	"time"
-
-	"github.com/AlekSi/pointer"
-)
-
-var dateTimeTestCases = []testCase{{
-	name: "2021",
-	v:    pointer.To(dateTimeType(time.Date(2021, 11, 1, 10, 18, 42, 123000000, time.UTC).Local())),
-	j:    `{"$d":1635761922123}`,
-}, {
-	name: "unix_zero",
-	v:    pointer.To(dateTimeType(time.Unix(0, 0))),
-	j:    `{"$d":0}`,
-}, {
-	name: "0",
-	v:    pointer.To(dateTimeType(time.Date(0, 1, 1, 0, 0, 0, 0, time.UTC).Local())),
-	j:    `{"$d":-62167219200000}`,
-}, {
-	name: "9999",
-	v:    pointer.To(dateTimeType(time.Date(9999, 12, 31, 23, 59, 59, 999000000, time.UTC).Local())),
-	j:    `{"$d":253402300799999}`,
-}}
-
-func TestDateTime(t *testing.T) {
-	t.Parallel()
-	testJSON(t, dateTimeTestCases, func() fjsontype { return new(dateTimeType) })
-}
diff --git a/internal/types/fjson/document.go b/internal/types/fjson/document.go
deleted file mode 100644
index 37d531d0dc14..000000000000
--- a/internal/types/fjson/document.go
+++ /dev/null
@@ -1,74 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"bytes"
-	"encoding/json"
-
-	"github.com/FerretDB/FerretDB/internal/types"
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// documentType represents BSON Document type.
-type documentType types.Document
-
-// fjsontype implements fjsontype interface.
-func (doc *documentType) fjsontype() {}
-
-// MarshalJSON implements fjsontype interface.
-func (doc *documentType) MarshalJSON() ([]byte, error) {
-	td := types.Document(*doc)
-
-	var buf bytes.Buffer
-
-	buf.WriteString(`{"$k":`)
-	keys := td.Keys()
-	if keys == nil {
-		keys = []string{}
-	}
-	b, err := json.Marshal(keys)
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-	buf.Write(b)
-
-	values := td.Values()
-
-	for i, key := range keys {
-		buf.WriteByte(',')
-
-		if b, err = json.Marshal(key); err != nil {
-			return nil, lazyerrors.Error(err)
-		}
-		buf.Write(b)
-		buf.WriteByte(':')
-
-		b, err := Marshal(values[i])
-		if err != nil {
-			return nil, lazyerrors.Error(err)
-		}
-
-		buf.Write(b)
-	}
-
-	buf.WriteByte('}')
-	return buf.Bytes(), nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*documentType)(nil)
-)
diff --git a/internal/types/fjson/document_test.go b/internal/types/fjson/document_test.go
deleted file mode 100644
index 560dd4ca2277..000000000000
--- a/internal/types/fjson/document_test.go
+++ /dev/null
@@ -1,217 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"testing"
-	"time"
-
-	"github.com/FerretDB/FerretDB/internal/types"
-	"github.com/FerretDB/FerretDB/internal/util/must"
-)
-
-func convertDocument(d *types.Document) *documentType {
-	res := documentType(*d)
-	return &res
-}
-
-var (
-	handshake1 = testCase{
-		name: "handshake1",
-		v: convertDocument(must.NotFail(types.NewDocument(
-			"ismaster", true,
-			"client", must.NotFail(types.NewDocument(
-				"driver", must.NotFail(types.NewDocument(
-					"name", "nodejs",
-					"version", "4.0.0-beta.6",
-				)),
-				"os", must.NotFail(types.NewDocument(
-					"type", "Darwin",
-					"name", "darwin",
-					"architecture", "x64",
-					"version", "20.6.0",
-				)),
-				"platform", "Node.js v14.17.3, LE (unified)|Node.js v14.17.3, LE (unified)",
-				"application", must.NotFail(types.NewDocument(
-					"name", "mongosh 1.0.1",
-				)),
-			)),
-			"compression", must.NotFail(types.NewArray("none")),
-			"loadBalanced", false,
-		))),
-		j: `{"$k":["ismaster","client","compression","loadBalanced"],"ismaster":true,` +
-			`"client":{"$k":["driver","os","platform","application"],"driver":{"$k":["name","version"],` +
-			`"name":"nodejs","version":"4.0.0-beta.6"},"os":{"$k":["type","name","architecture","version"],` +
-			`"type":"Darwin","name":"darwin","architecture":"x64","version":"20.6.0"},` +
-			`"platform":"Node.js v14.17.3, LE (unified)|Node.js v14.17.3, LE (unified)",` +
-			`"application":{"$k":["name"],"name":"mongosh 1.0.1"}},"compression":["none"],"loadBalanced":false}`,
-	}
-
-	handshake2 = testCase{
-		name: "handshake2",
-		v: convertDocument(must.NotFail(types.NewDocument(
-			"ismaster", true,
-			"client", must.NotFail(types.NewDocument(
-				"driver", must.NotFail(types.NewDocument(
-					"name", "nodejs",
-					"version", "4.0.0-beta.6",
-				)),
-				"os", must.NotFail(types.NewDocument(
-					"type", "Darwin",
-					"name", "darwin",
-					"architecture", "x64",
-					"version", "20.6.0",
-				)),
-				"platform", "Node.js v14.17.3, LE (unified)|Node.js v14.17.3, LE (unified)",
-				"application", must.NotFail(types.NewDocument(
-					"name", "mongosh 1.0.1",
-				)),
-			)),
-			"compression", must.NotFail(types.NewArray("none")),
-			"loadBalanced", false,
-		))),
-		j: `{"$k":["ismaster","client","compression","loadBalanced"],"ismaster":true,` +
-			`"client":{"$k":["driver","os","platform","application"],"driver":{"$k":["name","version"],` +
-			`"name":"nodejs","version":"4.0.0-beta.6"},"os":{"$k":["type","name","architecture","version"],` +
-			`"type":"Darwin","name":"darwin","architecture":"x64","version":"20.6.0"},` +
-			`"platform":"Node.js v14.17.3, LE (unified)|Node.js v14.17.3, LE (unified)",` +
-			`"application":{"$k":["name"],"name":"mongosh 1.0.1"}},"compression":["none"],"loadBalanced":false}`,
-	}
-
-	handshake3 = testCase{
-		name: "handshake3",
-		v: convertDocument(must.NotFail(types.NewDocument(
-			"buildInfo", int32(1),
-			"lsid", must.NotFail(types.NewDocument(
-				"id", types.Binary{
-					Subtype: types.BinaryUUID,
-					B: []byte{
-						0xa3, 0x19, 0xf2, 0xb4, 0xa1, 0x75, 0x40, 0xc7,
-						0xb8, 0xe7, 0xa3, 0xa3, 0x2e, 0xc2, 0x56, 0xbe,
-					},
-				},
-			)),
-			"$db", "admin",
-		))),
-		j: `{"$k":["buildInfo","lsid","$db"],"buildInfo":1,` +
-			`"lsid":{"$k":["id"],"id":{"$b":"oxnytKF1QMe456OjLsJWvg==","s":4}},"$db":"admin"}`,
-	}
-
-	handshake4 = testCase{
-		name: "handshake4",
-		v: convertDocument(must.NotFail(types.NewDocument(
-			"version", "5.0.0",
-			"gitVersion", "1184f004a99660de6f5e745573419bda8a28c0e9",
-			"modules", must.NotFail(types.NewArray()),
-			"allocator", "tcmalloc",
-			"javascriptEngine", "mozjs",
-			"sysInfo", "deprecated",
-			"versionArray", must.NotFail(types.NewArray(int32(5), int32(0), int32(0), int32(0))),
-			"openssl", must.NotFail(types.NewDocument(
-				"running", "OpenSSL 1.1.1f  31 Mar 2020",
-				"compiled", "OpenSSL 1.1.1f  31 Mar 2020",
-			)),
-			"buildEnvironment", must.NotFail(types.NewDocument(
-				"distmod", "ubuntu2004",
-				"distarch", "x86_64",
-				"cc", "/opt/mongodbtoolchain/v3/bin/gcc: gcc (GCC) 8.5.0",
-				"ccflags", "-Werror -include mongo/platform/basic.h -fasynchronous-unwind-tables -ggdb "+
-					"-Wall -Wsign-compare -Wno-unknown-pragmas -Winvalid-pch -fno-omit-frame-pointer "+
-					"-fno-strict-aliasing -O2 -march=sandybridge -mtune=generic -mprefer-vector-width=128 "+
-					"-Wno-unused-local-typedefs -Wno-unused-function -Wno-deprecated-declarations "+
-					"-Wno-unused-const-variable -Wno-unused-but-set-variable -Wno-missing-braces "+
-					"-fstack-protector-strong -Wa,--nocompress-debug-sections -fno-builtin-memcmp",
-				"cxx", "/opt/mongodbtoolchain/v3/bin/g++: g++ (GCC) 8.5.0",
-				"cxxflags", "-Woverloaded-virtual -Wno-maybe-uninitialized -fsized-deallocation -std=c++17",
-				"linkflags", "-Wl,--fatal-warnings -pthread -Wl,-z,now -fuse-ld=gold -fstack-protector-strong "+
-					"-Wl,--no-threads -Wl,--build-id -Wl,--hash-style=gnu -Wl,-z,noexecstack -Wl,--warn-execstack "+
-					"-Wl,-z,relro -Wl,--compress-debug-sections=none -Wl,-z,origin -Wl,--enable-new-dtags",
-				"target_arch", "x86_64",
-				"target_os", "linux",
-				"cppdefines", "SAFEINT_USE_INTRINSICS 0 PCRE_STATIC NDEBUG _XOPEN_SOURCE 700 _GNU_SOURCE "+
-					"_REENTRANT 1 _FORTIFY_SOURCE 2 BOOST_THREAD_VERSION 5 BOOST_THREAD_USES_DATETIME "+
-					"BOOST_SYSTEM_NO_DEPRECATED BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS "+
-					"BOOST_ENABLE_ASSERT_DEBUG_HANDLER BOOST_LOG_NO_SHORTHAND_NAMES BOOST_LOG_USE_NATIVE_SYSLOG "+
-					"BOOST_LOG_WITHOUT_THREAD_ATTR ABSL_FORCE_ALIGNED_ACCESS",
-			)),
-			"bits", int32(64),
-			"debug", false,
-			"maxBsonObjectSize", int32(16777216),
-			"storageEngines", must.NotFail(types.NewArray("devnull", "ephemeralForTest", "wiredTiger")),
-			"ok", float64(1),
-		))),
-		j: `{"$k":["version","gitVersion","modules","allocator","javascriptEngine","sysInfo","versionArray",` +
-			`"openssl","buildEnvironment","bits","debug","maxBsonObjectSize","storageEngines","ok"],` +
-			`"version":"5.0.0","gitVersion":"1184f004a99660de6f5e745573419bda8a28c0e9","modules":[],` +
-			`"allocator":"tcmalloc","javascriptEngine":"mozjs","sysInfo":"deprecated","versionArray":[5,0,0,0],` +
-			`"openssl":{"$k":["running","compiled"],"running":"OpenSSL 1.1.1f  31 Mar 2020",` +
-			`"compiled":"OpenSSL 1.1.1f  31 Mar 2020"},` +
-			`"buildEnvironment":{"$k":["distmod","distarch","cc","ccflags","cxx","cxxflags","linkflags",` +
-			`"target_arch","target_os","cppdefines"],"distmod":"ubuntu2004","distarch":"x86_64",` +
-			`"cc":"/opt/mongodbtoolchain/v3/bin/gcc: gcc (GCC) 8.5.0",` +
-			`"ccflags":"-Werror -include mongo/platform/basic.h -fasynchronous-unwind-tables -ggdb -Wall ` +
-			`-Wsign-compare -Wno-unknown-pragmas -Winvalid-pch -fno-omit-frame-pointer -fno-strict-aliasing ` +
-			`-O2 -march=sandybridge -mtune=generic -mprefer-vector-width=128 -Wno-unused-local-typedefs ` +
-			`-Wno-unused-function -Wno-deprecated-declarations -Wno-unused-const-variable ` +
-			`-Wno-unused-but-set-variable -Wno-missing-braces -fstack-protector-strong ` +
-			`-Wa,--nocompress-debug-sections -fno-builtin-memcmp",` +
-			`"cxx":"/opt/mongodbtoolchain/v3/bin/g++: g++ (GCC) 8.5.0",` +
-			`"cxxflags":"-Woverloaded-virtual -Wno-maybe-uninitialized -fsized-deallocation -std=c++17",` +
-			`"linkflags":"-Wl,--fatal-warnings -pthread -Wl,-z,now -fuse-ld=gold -fstack-protector-strong ` +
-			`-Wl,--no-threads -Wl,--build-id -Wl,--hash-style=gnu -Wl,-z,noexecstack -Wl,--warn-execstack ` +
-			`-Wl,-z,relro -Wl,--compress-debug-sections=none -Wl,-z,origin -Wl,--enable-new-dtags",` +
-			`"target_arch":"x86_64","target_os":"linux",` +
-			`"cppdefines":"SAFEINT_USE_INTRINSICS 0 PCRE_STATIC NDEBUG _XOPEN_SOURCE 700 _GNU_SOURCE ` +
-			`_REENTRANT 1 _FORTIFY_SOURCE 2 BOOST_THREAD_VERSION 5 BOOST_THREAD_USES_DATETIME ` +
-			`BOOST_SYSTEM_NO_DEPRECATED BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS BOOST_ENABLE_ASSERT_DEBUG_HANDLER ` +
-			`BOOST_LOG_NO_SHORTHAND_NAMES BOOST_LOG_USE_NATIVE_SYSLOG BOOST_LOG_WITHOUT_THREAD_ATTR ` +
-			`ABSL_FORCE_ALIGNED_ACCESS"},"bits":64,"debug":false,"maxBsonObjectSize":16777216,` +
-			`"storageEngines":["devnull","ephemeralForTest","wiredTiger"],"ok":{"$f":1}}`,
-	}
-
-	all = testCase{
-		name: "all",
-		v: convertDocument(must.NotFail(types.NewDocument(
-			"binary", must.NotFail(types.NewArray(
-				types.Binary{Subtype: types.BinaryUser, B: []byte{0x42}},
-				types.Binary{Subtype: types.BinaryGeneric, B: []byte{}},
-			)),
-			"bool", must.NotFail(types.NewArray(true, false)),
-			"datetime", must.NotFail(types.NewArray(
-				time.Date(2021, 7, 27, 9, 35, 42, 123000000, time.UTC).Local(),
-				time.Time{}.Local(),
-			)),
-			"double", must.NotFail(types.NewArray(42.13, 0.0)),
-			"int32", must.NotFail(types.NewArray(int32(42), int32(0))),
-			"int64", must.NotFail(types.NewArray(int64(42), int64(0))),
-			"objectID", must.NotFail(types.NewArray(types.ObjectID{0x42}, types.ObjectID{})),
-			"string", must.NotFail(types.NewArray("foo", "")),
-			"timestamp", must.NotFail(types.NewArray(types.Timestamp(42), types.Timestamp(0))),
-		))),
-		j: `{"$k":["binary","bool","datetime","double","int32","int64","objectID","string","timestamp"],` +
-			`"binary":[{"$b":"Qg==","s":128},{"$b":"","s":0}],"bool":[true,false],` +
-			`"datetime":[{"$d":1627378542123},{"$d":-62135596800000}],"double":[{"$f":42.13},{"$f":0}],` +
-			`"int32":[42,0],"int64":[{"$l":"42"},{"$l":"0"}],` +
-			`"objectID":[{"$o":"420000000000000000000000"},{"$o":"000000000000000000000000"}],` +
-			`"string":["foo",""],"timestamp":[{"$t":"42"},{"$t":"0"}]}`,
-	}
-
-	documentTestCases = []testCase{handshake1, handshake2, handshake3, handshake4, all}
-)
-
-func TestDocument(t *testing.T) {
-	t.Parallel()
-	testJSON(t, documentTestCases, func() fjsontype { return new(documentType) })
-}
diff --git a/internal/types/fjson/double.go b/internal/types/fjson/double.go
deleted file mode 100644
index 3f4dd36a9d67..000000000000
--- a/internal/types/fjson/double.go
+++ /dev/null
@@ -1,62 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"encoding/json"
-	"math"
-
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// doubleType represents BSON 64-bit binary floating point type.
-type doubleType float64
-
-// fjsontype implements fjsontype interface.
-func (d *doubleType) fjsontype() {}
-
-// doubleJSON is a JSON object representation of the doubleType.
-type doubleJSON struct {
-	F any `json:"$f"`
-}
-
-// MarshalJSON implements fjsontype interface.
-func (d *doubleType) MarshalJSON() ([]byte, error) {
-	f := float64(*d)
-	var o doubleJSON
-	switch {
-	case f == 0 && math.Signbit(f):
-		o.F = "-0"
-	case math.IsInf(f, 1):
-		o.F = "Infinity"
-	case math.IsInf(f, -1):
-		o.F = "-Infinity"
-	case math.IsNaN(f):
-		o.F = "NaN"
-	default:
-		o.F = f
-	}
-
-	res, err := json.Marshal(o)
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-	return res, nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*doubleType)(nil)
-)
diff --git a/internal/types/fjson/double_test.go b/internal/types/fjson/double_test.go
deleted file mode 100644
index 19cd01c27f5a..000000000000
--- a/internal/types/fjson/double_test.go
+++ /dev/null
@@ -1,61 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"math"
-	"testing"
-
-	"github.com/AlekSi/pointer"
-)
-
-var doubleTestCases = []testCase{{
-	name: "42.13",
-	v:    pointer.To(doubleType(42.13)),
-	j:    `{"$f":42.13}`,
-}, {
-	name: "zero",
-	v:    pointer.To(doubleType(math.Copysign(0, +1))),
-	j:    `{"$f":0}`,
-}, {
-	name: "negative zero",
-	v:    pointer.To(doubleType(math.Copysign(0, -1))),
-	j:    `{"$f":"-0"}`,
-}, {
-	name: "max float64",
-	v:    pointer.To(doubleType(math.MaxFloat64)),
-	j:    `{"$f":1.7976931348623157e+308}`,
-}, {
-	name: "smallest positive float64",
-	v:    pointer.To(doubleType(math.SmallestNonzeroFloat64)),
-	j:    `{"$f":5e-324}`,
-}, {
-	name: "+Infinity",
-	v:    pointer.To(doubleType(math.Inf(+1))),
-	j:    `{"$f":"Infinity"}`,
-}, {
-	name: "-Infinity",
-	v:    pointer.To(doubleType(math.Inf(-1))),
-	j:    `{"$f":"-Infinity"}`,
-}, {
-	name: "NaN",
-	v:    pointer.To(doubleType(math.NaN())),
-	j:    `{"$f":"NaN"}`,
-}}
-
-func TestDouble(t *testing.T) {
-	t.Parallel()
-	testJSON(t, doubleTestCases, func() fjsontype { return new(doubleType) })
-}
diff --git a/internal/types/fjson/fjson.go b/internal/types/fjson/fjson.go
deleted file mode 100644
index 8ebfb0652fbc..000000000000
--- a/internal/types/fjson/fjson.go
+++ /dev/null
@@ -1,148 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Package fjson provides converters to FJSON (JSON with some extensions) for built-in and `types` types.
-//
-// See contributing guidelines and documentation for package `types` for details.
-//
-// # Mapping
-//
-// Composite types
-//
-//	Alias      types package    fjson package         JSON representation
-//
-//	object     *types.Document  *fjson.documentType   {"$k": ["<key 1>", "<key 2>", ...], "<key 1>": <value 1>, "<key 2>": <value 2>, ...}
-//	array      *types.Array     *fjson.arrayType      JSON array
-//
-// Scalar types
-//
-//	Alias      types package    fjson package         JSON representation
-//
-//	double     float64          *fjson.doubleType     {"$f": JSON number} or {"$f": "Infinity|-Infinity|NaN"}
-//	string     string           *fjson.stringType     JSON string
-//	binData    types.Binary     *fjson.binaryType     {"$b": "<base 64 string>", "s": <subtype number>}
-//	objectId   types.ObjectID   *fjson.objectIDType   {"$o": "<ObjectID as 24 character hex string"}
-//	bool       bool             *fjson.boolType       JSON true / false values
-//	date       time.Time        *fjson.dateTimeType   {"$d": milliseconds since epoch as JSON number}
-//	null       types.NullType   *fjson.nullType       JSON null
-//	regex      types.Regex      *fjson.regexType      {"$r": "<string without terminating 0x0>", "o": "<string without terminating 0x0>"}
-//	int        int32            *fjson.int32Type      JSON number
-//	timestamp  types.Timestamp  *fjson.timestampType  {"$t": "<number as string>"}
-//	long       int64            *fjson.int64Type      {"$l": "<number as string>"}
-//
-//nolint:lll // for readability
-//nolint:dupword // false positive
-package fjson
-
-import (
-	"encoding/json"
-	"fmt"
-	"time"
-
-	"github.com/AlekSi/pointer"
-
-	"github.com/FerretDB/FerretDB/internal/types"
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// fjsontype is a type that can be marshaled to FJSON.
-//
-//sumtype:decl
-type fjsontype interface {
-	fjsontype() // seal for sumtype
-
-	json.Marshaler
-}
-
-// fromFJSON converts fjsontype value to matching built-in or types' package value.
-func fromFJSON(v fjsontype) any {
-	switch v := v.(type) {
-	case *documentType:
-		return pointer.To(types.Document(*v))
-	case *arrayType:
-		return pointer.To(types.Array(*v))
-	case *doubleType:
-		return float64(*v)
-	case *stringType:
-		return string(*v)
-	case *binaryType:
-		return types.Binary(*v)
-	case *objectIDType:
-		return types.ObjectID(*v)
-	case *boolType:
-		return bool(*v)
-	case *dateTimeType:
-		return time.Time(*v)
-	case *nullType:
-		return types.Null
-	case *regexType:
-		return types.Regex(*v)
-	case *int32Type:
-		return int32(*v)
-	case *timestampType:
-		return types.Timestamp(*v)
-	case *int64Type:
-		return int64(*v)
-	}
-
-	panic(fmt.Sprintf("not reached: %T", v)) // for sumtype to work
-}
-
-// toFJSON converts built-in or types' package value to fjsontype value.
-func toFJSON(v any) fjsontype {
-	switch v := v.(type) {
-	case *types.Document:
-		return pointer.To(documentType(*v))
-	case *types.Array:
-		return pointer.To(arrayType(*v))
-	case float64:
-		return pointer.To(doubleType(v))
-	case string:
-		return pointer.To(stringType(v))
-	case types.Binary:
-		return pointer.To(binaryType(v))
-	case types.ObjectID:
-		return pointer.To(objectIDType(v))
-	case bool:
-		return pointer.To(boolType(v))
-	case time.Time:
-		return pointer.To(dateTimeType(v))
-	case types.NullType:
-		return pointer.To(nullType(v))
-	case types.Regex:
-		return pointer.To(regexType(v))
-	case int32:
-		return pointer.To(int32Type(v))
-	case types.Timestamp:
-		return pointer.To(timestampType(v))
-	case int64:
-		return pointer.To(int64Type(v))
-	}
-
-	panic(fmt.Sprintf("not reached: %T", v)) // for sumtype to work
-}
-
-// Marshal encodes given built-in or types' package value into fjson.
-func Marshal(v any) ([]byte, error) {
-	if v == nil {
-		panic("v is nil")
-	}
-
-	b, err := toFJSON(v).MarshalJSON()
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-
-	return b, nil
-}
diff --git a/internal/types/fjson/fjson_test.go b/internal/types/fjson/fjson_test.go
deleted file mode 100644
index e531c1397d48..000000000000
--- a/internal/types/fjson/fjson_test.go
+++ /dev/null
@@ -1,57 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-type testCase struct {
-	name string
-	v    fjsontype
-	j    string
-}
-
-func testJSON(t *testing.T, testCases []testCase, newFunc func() fjsontype) {
-	for _, tc := range testCases {
-		tc := tc
-		t.Run(tc.name, func(t *testing.T) {
-			require.NotEmpty(t, tc.name, "name should not be empty")
-			require.NotNil(t, tc.v, "v should not be nil")
-			require.NotEmpty(t, tc.j, "j should not be empty")
-
-			t.Parallel()
-
-			t.Run("MarshalJSON", func(t *testing.T) {
-				t.Parallel()
-
-				actualJ, err := tc.v.MarshalJSON()
-				require.NoError(t, err)
-				assert.Equal(t, tc.j, string(actualJ))
-			})
-
-			t.Run("Marshal", func(t *testing.T) {
-				t.Parallel()
-
-				actualJ, err := Marshal(fromFJSON(tc.v))
-				require.NoError(t, err)
-				assert.Equal(t, tc.j, string(actualJ))
-			})
-		})
-	}
-}
diff --git a/internal/types/fjson/int32.go b/internal/types/fjson/int32.go
deleted file mode 100644
index 233961c9ed5a..000000000000
--- a/internal/types/fjson/int32.go
+++ /dev/null
@@ -1,41 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"encoding/json"
-
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// int32Type represents BSON 32-bit integer type.
-type int32Type int32
-
-// fjsontype implements fjsontype interface.
-func (i *int32Type) fjsontype() {}
-
-// MarshalJSON implements fjsontype interface.
-func (i *int32Type) MarshalJSON() ([]byte, error) {
-	res, err := json.Marshal(int32(*i))
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-	return res, nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*int32Type)(nil)
-)
diff --git a/internal/types/fjson/int32_test.go b/internal/types/fjson/int32_test.go
deleted file mode 100644
index d5b9ad88ebcf..000000000000
--- a/internal/types/fjson/int32_test.go
+++ /dev/null
@@ -1,45 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"math"
-	"testing"
-
-	"github.com/AlekSi/pointer"
-)
-
-var int32TestCases = []testCase{{
-	name: "42",
-	v:    pointer.To(int32Type(42)),
-	j:    `42`,
-}, {
-	name: "zero",
-	v:    pointer.To(int32Type(0)),
-	j:    `0`,
-}, {
-	name: "max int32",
-	v:    pointer.To(int32Type(math.MaxInt32)),
-	j:    `2147483647`,
-}, {
-	name: "min int32",
-	v:    pointer.To(int32Type(math.MinInt32)),
-	j:    `-2147483648`,
-}}
-
-func TestInt32(t *testing.T) {
-	t.Parallel()
-	testJSON(t, int32TestCases, func() fjsontype { return new(int32Type) })
-}
diff --git a/internal/types/fjson/int64.go b/internal/types/fjson/int64.go
deleted file mode 100644
index 9da844df1611..000000000000
--- a/internal/types/fjson/int64.go
+++ /dev/null
@@ -1,48 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"encoding/json"
-
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// int64Type represents BSON 64-bit integer type.
-type int64Type int64
-
-// fjsontype implements fjsontype interface.
-func (i *int64Type) fjsontype() {}
-
-// int64JSON is a JSON object representation of the int64Type.
-type int64JSON struct {
-	L int64 `json:"$l,string"`
-}
-
-// MarshalJSON implements fjsontype interface.
-func (i *int64Type) MarshalJSON() ([]byte, error) {
-	res, err := json.Marshal(int64JSON{
-		L: int64(*i),
-	})
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-	return res, nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*int64Type)(nil)
-)
diff --git a/internal/types/fjson/int64_test.go b/internal/types/fjson/int64_test.go
deleted file mode 100644
index 0a1fa4456c41..000000000000
--- a/internal/types/fjson/int64_test.go
+++ /dev/null
@@ -1,45 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"math"
-	"testing"
-
-	"github.com/AlekSi/pointer"
-)
-
-var int64TestCases = []testCase{{
-	name: "42",
-	v:    pointer.To(int64Type(42)),
-	j:    `{"$l":"42"}`,
-}, {
-	name: "zero",
-	v:    pointer.To(int64Type(0)),
-	j:    `{"$l":"0"}`,
-}, {
-	name: "max int64",
-	v:    pointer.To(int64Type(math.MaxInt64)),
-	j:    `{"$l":"9223372036854775807"}`,
-}, {
-	name: "min int64",
-	v:    pointer.To(int64Type(math.MinInt64)),
-	j:    `{"$l":"-9223372036854775808"}`,
-}}
-
-func TestInt64(t *testing.T) {
-	t.Parallel()
-	testJSON(t, int64TestCases, func() fjsontype { return new(int64Type) })
-}
diff --git a/internal/types/fjson/null.go b/internal/types/fjson/null.go
deleted file mode 100644
index 410d490e750c..000000000000
--- a/internal/types/fjson/null.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import "github.com/FerretDB/FerretDB/internal/types"
-
-// nullType represents BSON Null type.
-type nullType types.NullType
-
-// fjsontype implements fjsontype interface.
-func (*nullType) fjsontype() {}
-
-// MarshalJSON implements fjsontype interface.
-func (*nullType) MarshalJSON() ([]byte, error) {
-	return []byte("null"), nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*nullType)(nil)
-)
diff --git a/internal/types/fjson/null_test.go b/internal/types/fjson/null_test.go
deleted file mode 100644
index 3cfe5d6fdc0d..000000000000
--- a/internal/types/fjson/null_test.go
+++ /dev/null
@@ -1,32 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"testing"
-
-	"github.com/AlekSi/pointer"
-)
-
-var nullTestCases = []testCase{{
-	name: "null",
-	v:    pointer.To(nullType{}),
-	j:    `null`,
-}}
-
-func TestNull(t *testing.T) {
-	t.Parallel()
-	testJSON(t, nullTestCases, func() fjsontype { return new(nullType) })
-}
diff --git a/internal/types/fjson/object_id.go b/internal/types/fjson/object_id.go
deleted file mode 100644
index 1c79fddab10e..000000000000
--- a/internal/types/fjson/object_id.go
+++ /dev/null
@@ -1,50 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"encoding/hex"
-	"encoding/json"
-
-	"github.com/FerretDB/FerretDB/internal/types"
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// objectIDType represents BSON ObjectId type.
-type objectIDType types.ObjectID
-
-// fjsontype implements fjsontype interface.
-func (obj *objectIDType) fjsontype() {}
-
-// objectIDJSON is a JSON object representation of the objectIDType.
-type objectIDJSON struct {
-	O string `json:"$o"`
-}
-
-// MarshalJSON implements fjsontype interface.
-func (obj *objectIDType) MarshalJSON() ([]byte, error) {
-	res, err := json.Marshal(objectIDJSON{
-		O: hex.EncodeToString(obj[:]),
-	})
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-	return res, nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*objectIDType)(nil)
-)
diff --git a/internal/types/fjson/object_id_test.go b/internal/types/fjson/object_id_test.go
deleted file mode 100644
index 7cacdfaa560b..000000000000
--- a/internal/types/fjson/object_id_test.go
+++ /dev/null
@@ -1,32 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"testing"
-
-	"github.com/AlekSi/pointer"
-)
-
-var objectIDTestCases = []testCase{{
-	name: "normal",
-	v:    pointer.To(objectIDType{0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01}),
-	j:    `{"$o":"010101010101010101010101"}`,
-}}
-
-func TestObjectID(t *testing.T) {
-	t.Parallel()
-	testJSON(t, objectIDTestCases, func() fjsontype { return new(objectIDType) })
-}
diff --git a/internal/types/fjson/regex.go b/internal/types/fjson/regex.go
deleted file mode 100644
index 1c9dd8badd80..000000000000
--- a/internal/types/fjson/regex.go
+++ /dev/null
@@ -1,51 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"encoding/json"
-
-	"github.com/FerretDB/FerretDB/internal/types"
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// regexType represents BSON Regular expression type.
-type regexType types.Regex
-
-// fjsontype implements fjsontype interface.
-func (regex *regexType) fjsontype() {}
-
-// regexJSON is a JSON object representation of the regexType.
-type regexJSON struct {
-	R string `json:"$r"`
-	O string `json:"o"`
-}
-
-// MarshalJSON implements fjsontype interface.
-func (regex *regexType) MarshalJSON() ([]byte, error) {
-	res, err := json.Marshal(regexJSON{
-		R: regex.Pattern,
-		O: regex.Options,
-	})
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-	return res, nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*regexType)(nil)
-)
diff --git a/internal/types/fjson/regex_test.go b/internal/types/fjson/regex_test.go
deleted file mode 100644
index 535349098361..000000000000
--- a/internal/types/fjson/regex_test.go
+++ /dev/null
@@ -1,36 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"testing"
-
-	"github.com/AlekSi/pointer"
-)
-
-var regexTestCases = []testCase{{
-	name: "normal",
-	v:    pointer.To(regexType{Pattern: "hoffman", Options: "i"}),
-	j:    `{"$r":"hoffman","o":"i"}`,
-}, {
-	name: "empty",
-	v:    pointer.To(regexType{Pattern: "", Options: ""}),
-	j:    `{"$r":"","o":""}`,
-}}
-
-func TestRegex(t *testing.T) {
-	t.Parallel()
-	testJSON(t, regexTestCases, func() fjsontype { return new(regexType) })
-}
diff --git a/internal/types/fjson/string.go b/internal/types/fjson/string.go
deleted file mode 100644
index 6a61ec3a286d..000000000000
--- a/internal/types/fjson/string.go
+++ /dev/null
@@ -1,41 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"encoding/json"
-
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// stringType represents BSON UTF-8 string type.
-type stringType string
-
-// fjsontype implements fjsontype interface.
-func (str *stringType) fjsontype() {}
-
-// MarshalJSON implements fjsontype interface.
-func (str *stringType) MarshalJSON() ([]byte, error) {
-	res, err := json.Marshal(string(*str))
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-	return res, nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*stringType)(nil)
-)
diff --git a/internal/types/fjson/string_test.go b/internal/types/fjson/string_test.go
deleted file mode 100644
index 17a8f61d949d..000000000000
--- a/internal/types/fjson/string_test.go
+++ /dev/null
@@ -1,40 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"testing"
-
-	"github.com/AlekSi/pointer"
-)
-
-var stringTestCases = []testCase{{
-	name: "foo",
-	v:    pointer.To(stringType("foo")),
-	j:    `"foo"`,
-}, {
-	name: "empty",
-	v:    pointer.To(stringType("")),
-	j:    `""`,
-}, {
-	name: "zero",
-	v:    pointer.To(stringType("\x00")),
-	j:    `"\u0000"`,
-}}
-
-func TestString(t *testing.T) {
-	t.Parallel()
-	testJSON(t, stringTestCases, func() fjsontype { return new(stringType) })
-}
diff --git a/internal/types/fjson/timestamp.go b/internal/types/fjson/timestamp.go
deleted file mode 100644
index c337bfd16b85..000000000000
--- a/internal/types/fjson/timestamp.go
+++ /dev/null
@@ -1,49 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"encoding/json"
-
-	"github.com/FerretDB/FerretDB/internal/types"
-	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
-)
-
-// timestampType represents BSON Timestamp type.
-type timestampType types.Timestamp
-
-// fjsontype implements fjsontype interface.
-func (ts *timestampType) fjsontype() {}
-
-// timestampJSON is a JSON object representation of the timestampType.
-type timestampJSON struct {
-	T uint64 `json:"$t,string"`
-}
-
-// MarshalJSON implements fjsontype interface.
-func (ts *timestampType) MarshalJSON() ([]byte, error) {
-	res, err := json.Marshal(timestampJSON{
-		T: uint64(*ts),
-	})
-	if err != nil {
-		return nil, lazyerrors.Error(err)
-	}
-	return res, nil
-}
-
-// check interfaces
-var (
-	_ fjsontype = (*timestampType)(nil)
-)
diff --git a/internal/types/fjson/timestamp_test.go b/internal/types/fjson/timestamp_test.go
deleted file mode 100644
index 804630995529..000000000000
--- a/internal/types/fjson/timestamp_test.go
+++ /dev/null
@@ -1,36 +0,0 @@
-// Copyright 2021 FerretDB Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package fjson
-
-import (
-	"testing"
-
-	"github.com/AlekSi/pointer"
-)
-
-var timestampTestCases = []testCase{{
-	name: "one",
-	v:    pointer.To(timestampType(1)),
-	j:    `{"$t":"1"}`,
-}, {
-	name: "zero",
-	v:    pointer.To(timestampType(0)),
-	j:    `{"$t":"0"}`,
-}}
-
-func TestTimestamp(t *testing.T) {
-	t.Parallel()
-	testJSON(t, timestampTestCases, func() fjsontype { return new(timestampType) })
-}
diff --git a/internal/types/types.go b/internal/types/types.go
index e4e541ba2302..137dc35d8fb7 100644
--- a/internal/types/types.go
+++ b/internal/types/types.go
@@ -14,12 +14,11 @@
 
 // Package types provides Go types matching BSON types that don't have built-in Go equivalents.
 //
-// All BSON types have four representations in FerretDB:
+// All BSON types have three representations in FerretDB:
 //
 //  1. As they are used in "business logic" / handlers - `types` package.
-//  2. As they are used for logging - `fjson` package.
-//  3. As they are used in the wire protocol implementation - `bson` package.
-//  4. As they are used to store data in SQL based databases - `sjson` package.
+//  2. As they are used in the wire protocol implementation and for logging - `bson` package.
+//  3. As they are used to store data in SQL based databases - `sjson` package.
 //
 // The reason for that is a separation of concerns: to avoid method names clashes, to simplify type asserts,
 // to make refactorings and optimizations easier, etc.