crx3

🤖 AI-ready Chrome extension tooling via Model Context Protocol (MCP)
A modern, comprehensive toolset for CRX3 Chrome extension management — pack, unpack, download, analyze, and automate with AI.

👉 MCP Configuration Guide — Setup instructions for Cursor, Claude Desktop, Opencode, Crush & more.

✨ Features

🤖 MCP Integration

This tool is AI-compatible through Model Context Protocol (MCP), enabling seamless interaction with:

• ✅ Cursor IDE — Chat with your extensions, auto-generate packs
• ✅ Claude Desktop — Natural language CRX3 operations
• ✅ Opencode — Automated extension workflows
• ✅ Crush — AI-assisted extension management
• ✅ Any MCP client — HTTP/SSE or stdio transport

Automate CRX3 operations through natural language commands powered by AI.

# Start MCP server (stdio mode for local AI clients)
crx3 mcp

# Or run over HTTP/SSE for remote clients 
crx3 mcp --listen=locahost:3000
crx3 mcp --listen=localhost:3000 --sse 

📖 See MCP.md for detailed setup instructions.

🛠️ Command Reference

💡 All commands support --help for detailed usage: crx3 pack --help

📦 Installation

Via Homebrew (macOS/Linux)

brew tap mmadfox/tap https://github.com/mmadfox/homebrew-tap
brew install mmadfox/tap/crx3

Via install.sh (Linux/macOS)

sudo curl -sSfL https://raw.githubusercontent.com/mmadfox/go-crx3/master/install.sh | bash -s

Via Go

go install github.com/mediabuyerbot/go-crx3/crx3@latest

Via Release Binary

Download pre-built binaries from Releases.

Verify Installation

crx3 version
# Output: crx3 version x.y.z

🚀 Quick Start Examples

Pack an extension

# Basic pack (auto-generates key if missing)
crx3 pack ./my-extension -o ./build/extension.crx3

# Pack with existing private key
crx3 pack ./my-extension -p ./keys/private.pem -o ./build/extension.crx3

Unpack and inspect

# Extract CRX3 to directory
crx3 unpack ./extension.crx3 -o ./extracted 

# View manifest
cat ./extracted/manifest.json

# Without creating a subdirectory 
crx3 unpack ./extension.crx3 -o ./extracted -s

Download from Chrome Web Store

# By extension ID
crx3 download blipmdconlkpinefehnmjammfjpmpbjk -o ./extensions/lighthouse

# Wihtout auto unpack
crx3 download blipmdconlkpinefehnmjammfjpmpbjk --unpack=false

# By full URL
crx3 download "https://chrome.google.com/webstore/detail/lighthouse/blipmdconlkpinefehnmjammfjpmpbjk"

Generate extension ID

# From existing CRX3 file
crx3 id ./extension.crx3
# Output: dgmchnekcpklnjppdmmjlgpmpohmpmgp

# From public key
crx3 id -k ./keys/public.pem

Key management

# Generate new RSA key pair
crx3 keygen ./keys/my-key.pem

# The same command creates both private.pem and extracts public key internally

Archive operations

# Zip a directory
crx3 zip ./my-extension -o ./archive.zip

# Unzip archive
crx3 unzip ./archive.zip -o ./output

Base64 encoding (for embedding)

# Encode CRX3 to base64
crx3 base64 ./extension.crx3

# Save to file
crx3 base64 ./extension.crx3 -o ./encoded.txt

Search Chrome Web Store

# Search by keyword
crx3 search "ad blocker" 

💻 Code Examples (Go API)

Pack a zip file or directory

import crx3 "github.com/mediabuyerbot/go-crx3"

// Basic pack
if err := crx3.Extension("/path/to/file.zip").Pack(nil); err != nil {
    panic(err)
}

// Pack with private key
pk, err := crx3.LoadPrivateKey("/path/to/key.pem")
if err != nil { panic(err) }
if err := crx3.Extension("/path/to/file.zip").Pack(pk); err != nil {
    panic(err)
}

// Pack to custom output path
if err := crx3.Extension("/path/to/file.zip").PackTo("/path/to/ext.crx", pk); err != nil {
    panic(err)
}

Unpack extension

import crx3 "github.com/mediabuyerbot/go-crx3"

if err := crx3.Extension("/path/to/ext.crx").Unpack(); err != nil {
   panic(err)
}

Download from Web Store

import crx3 "github.com/mediabuyerbot/go-crx3"

extensionID := "blipmdconlkpinefehnmjammfjpmpbjk"
if err := crx3.DownloadFromWebStore(extensionID, "/path/to/ext.crx"); err != nil {
    panic(err)
}

Generate/Load Keys

import crx3 "github.com/mediabuyerbot/go-crx3"

// Generate new key
pk, err := crx3.NewPrivateKey()
if err != nil { panic(err) }

// Save and load
if err := crx3.SavePrivateKey("/path/to/key.pem", pk); err != nil { panic(err) }
pk, err = crx3.LoadPrivateKey("/path/to/key.pem")

Helper Functions

import crx3 "github.com/mediabuyerbot/go-crx3"

// Type detection
crx3.Extension("/path/to/ext.zip").IsZip()   // true
crx3.Extension("/path/to/ext").IsDir()       // true  
crx3.Extension("/path/to/ext.crx").IsCRX3()  // true

// Get extension ID
id, err := crx3.Extension("/path/to/ext.crx").ID()

Base64 Encoding

import crx3 "github.com/mediabuyerbot/go-crx3"

b, err := crx3.Extension("/path/to/ext.crx").Base64()
if err != nil { panic(err) }
fmt.Println(string(b))

⚙️ Advanced Usage

MCP Server Modes

Common Flags

# Global flags
--workdir, -w    # Set working directory (default: .)
--logfile, -f    # Path to log file (default: stderr)

# MCP-specific flags  
--listen, -l     # Run HTTP server at address (e.g., :3000)
--tools.disabled, -d  # Disable specific tools (comma-separated)
--tools.show, -s      # List available tools and exit

Example: Secure MCP Setup

# Run MCP with restricted tools and sandboxed directory
crx3 mcp \
  --workdir=/safe/extensions \
  --tools.disabled=crx3_download,crx3_unpack \
  --logfile=/var/log/crx3-mcp.log

🧪 Development

# Generate protobuf code
make proto

# Run tests with coverage
make test/cover

# View coverage report
go tool cover -html=coverage.out

📚 Resources

• 📘 CRX3 Format Spec
• 🤖 Model Context Protocol
• 🐛 Bug Reports & Issues

📄 License

go-crx3 is released under the Apache 2.0 License.
See LICENSE for details.