diff --git a/README.md b/README.md
index c8cf56232..62557663f 100644
--- a/README.md
+++ b/README.md
@@ -38,6 +38,10 @@ And much more..
 
 -   [Vue](https://vuejs.org/)
 
+### Module Systems
+
+[Happy DOM](https://github.com/capricorn86/happy-dom) has support for both [ESM](https://nodejs.org/api/esm.html#introduction) and [CommonJS](https://nodejs.org/api/modules.html#modules-commonjs-modules).
+
 # Packages
 
 This repository is a _Monorepo_. Each package lives under `packages/<package>`.
diff --git a/packages/global-registrator/README.md b/packages/global-registrator/README.md
index 65bcf7285..99c05561a 100644
--- a/packages/global-registrator/README.md
+++ b/packages/global-registrator/README.md
@@ -38,6 +38,10 @@ And much more..
 
 - [Vue](https://vuejs.org/)
 
+### Module Systems
+
+[Happy DOM](https://github.com/capricorn86/happy-dom) has support for both [ESM](https://nodejs.org/api/esm.html#introduction) and [CommonJS](https://nodejs.org/api/modules.html#modules-commonjs-modules).
+
 # Installation
 
 ```bash
diff --git a/packages/happy-dom/README.md b/packages/happy-dom/README.md
index 9327e7ab6..da6e6081e 100644
--- a/packages/happy-dom/README.md
+++ b/packages/happy-dom/README.md
@@ -36,6 +36,10 @@ And much more..
 
 - [Vue](https://vuejs.org/)
 
+### Module Systems
+
+[Happy DOM](https://github.com/capricorn86/happy-dom) has support for both [ESM](https://nodejs.org/api/esm.html#introduction) and [CommonJS](https://nodejs.org/api/modules.html#modules-commonjs-modules).
+
 # Installation
 
 ```bash
diff --git a/packages/integration-test/README.md b/packages/integration-test/README.md
index 65bcf7285..6af75a522 100644
--- a/packages/integration-test/README.md
+++ b/packages/integration-test/README.md
@@ -1,99 +1 @@
-![Happy DOM Logo](https://github.com/capricorn86/happy-dom/raw/master/docs/happy-dom-logo.jpg)
-
-# About
-
-[Happy DOM](https://github.com/capricorn86/happy-dom) is a JavaScript implementation of a web browser without its graphical user interface. It includes many web standards from WHATWG [DOM](https://dom.spec.whatwg.org/) and [HTML](https://html.spec.whatwg.org/multipage/).
-
-The goal of [Happy DOM](https://github.com/capricorn86/happy-dom) is to emulate enough of a web browser to be useful for testing, scraping web sites and server-side rendering.
-
-[Happy DOM](https://github.com/capricorn86/happy-dom) focuses heavily on performance and can be used as an alternative to [JSDOM](https://github.com/jsdom/jsdom).
-
-This package contains a utility that registers [Happy DOM](https://github.com/capricorn86/happy-dom) globally, which makes it possible to use [Happy DOM](https://github.com/capricorn86/happy-dom) for testing in a Node environment.
-
-### DOM Features
-
-- Custom Elements (Web Components)
-
-- Shadow Root (Shadow DOM)
-
-- Declarative Shadow DOM
-
-- Mutation Observer
-
-- Tree Walker
-
-- Fetch
-
-And much more..
-
-### Works With
-
-- [Google LitHTML](https://lit-html.polymer-project.org)
-
-- [Google LitElement](https://lit-element.polymer-project.org)
-
-- [React](https://reactjs.org)
-
-- [Angular](https://angular.io/)
-
-- [Vue](https://vuejs.org/)
-
-# Installation
-
-```bash
-npm install @happy-dom/global-registrator --save-dev
-```
-
-# Usage
-
-## Register
-
-```javascript
-import { GlobalRegistrator } from '@happy-dom/global-registrator';
-
-GlobalRegistrator.register();
-
-document.body.innerHTML = `<button>My button</button>`;
-
-const button = document.querySelector('button');
-
-// Outputs: "My button"
-console.log(button.innerText);
-```
-
-## Unregister
-
-```javascript
-import { GlobalRegistrator } from '@happy-dom/global-registrator';
-
-GlobalRegistrator.register();
-
-GlobalRegistrator.unregister();
-
-// Outputs: "undefined"
-console.log(global.document);
-```
-
-# Documentation
-
-Read more about how Happy DOM works in our [documentation](https://github.com/capricorn86/happy-dom/wiki).
-
-# Performance
-
-| Operation                            | JSDOM   | Happy DOM |
-| ------------------------------------ | ------- | --------- |
-| Import / Require                     | 333 ms  | 45 ms     |
-| Parse HTML                           | 256 ms  | 26 ms     |
-| Serialize HTML                       | 65 ms   | 8 ms      |
-| Render custom element                | 214 ms  | 19 ms     |
-| querySelectorAll('tagname')          | 4.9 ms  | 0.7 ms    |
-| querySelectorAll('.class')           | 6.4 ms  | 3.7 ms    |
-| querySelectorAll('[attribute]')      | 4.0 ms  | 1.7 ms    |
-| querySelectorAll('[class~="name"]')  | 5.5 ms  | 2.9 ms    |
-| querySelectorAll(':nth-child(2n+1)') | 10.4 ms | 3.8 ms    |
-
-[See how the test was done here](https://github.com/capricorn86/happy-dom-performance-test)
-
-# Sponsors
-
-[<img alt="RTVision" width="120px" src="https://avatars.githubusercontent.com/u/8292810?s=200&v=4" />](https://rtvision.com)
+This package is used internally for testing the integration of Happy DOM in various environments.
diff --git a/packages/jest-environment/README.md b/packages/jest-environment/README.md
index ded15450b..a4e1328c9 100644
--- a/packages/jest-environment/README.md
+++ b/packages/jest-environment/README.md
@@ -38,6 +38,10 @@ And much more..
 
 - [Vue](https://vuejs.org/)
 
+### Module Systems
+
+[Happy DOM](https://github.com/capricorn86/happy-dom) has support for both [ESM](https://nodejs.org/api/esm.html#introduction) and [CommonJS](https://nodejs.org/api/modules.html#modules-commonjs-modules). However, [@happy-dom/jest-environment](https://github.com/capricorn86/happy-dom/packages/jest-environment) only has support for [CommonJS](https://nodejs.org/api/modules.html#modules-commonjs-modules) because of limitations with [Jest](https://jestjs.io/).
+
 # Installation
 
 ```bash