go-useragent

go-useragent is a high-performance Go library designed to parse browser name and version, operating system, and device type information from user-agent strings with sub-microsecond parsing times.

It achieves this efficiency by using a trie data structure to store and rapidly look up user-agent tokens. Utilizing heuristic rules, the library tokenizes a list of user-agent strings into a trie during startup. Subsequently, during runtime, the parsing process involves a straightforward lookup operation.

Installation

go get -u github.com/medama-io/go-useragent

Example

package main

import (
	"fmt"
	"github.com/medama-io/go-useragent"
)

func main() {
	// Create a new parser. Initialize only once during application startup.
	ua := useragent.NewParser()

	// Example user-agent string.
	str := "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36"

	// Parse the user-agent string.
	agent := ua.Parse(str)

	// Access parsed information using agent fields.
	fmt.Println(agent.Browser)  // Chrome
	fmt.Println(agent.OS)       // Windows
	fmt.Println(agent.Version)  // 118.0.0.0
	fmt.Println(agent.Desktop)  // true
	fmt.Println(agent.Mobile)   // false
	fmt.Println(agent.Tablet)   // false
	fmt.Println(agent.TV)       // false
	fmt.Println(agent.Bot)      // false

	// Helper functions.
	fmt.Println(agent.GetMajorVersion())  // 118
}

Refer to the pkg.go.dev documentation for more details on available fields and their meanings.

Acknowledgements

• The library draws inspiration from the techniques outlined in this Raygun blog post.