# Chromedp — Drive Browsers with the Chrome DevTools Protocol in Go

> Pure Go library for controlling browsers via the Chrome DevTools Protocol, without external dependencies like Selenium or PhantomJS.

## Install

Save in your project root:

# Chromedp — Drive Browsers with the Chrome DevTools Protocol in Go

## Quick Use
```go
package main

import (
    "context"
    "fmt"
    "github.com/chromedp/chromedp"
)

func main() {
    ctx, cancel := chromedp.NewContext(context.Background())
    defer cancel()
    var title string
    chromedp.Run(ctx,
        chromedp.Navigate("https://example.com"),
        chromedp.Title(&title),
    )
    fmt.Println(title)
}
```

## Introduction
Chromedp is a pure Go package for driving browsers using the Chrome DevTools Protocol (CDP). It provides a high-level API for navigating pages, filling forms, clicking elements, taking screenshots, and extracting data, all without requiring Selenium, WebDriver, or any external binary dependencies beyond a Chrome or Chromium installation.

## What Chromedp Does
- Controls Chrome and Chromium browsers programmatically via CDP
- Navigates pages, clicks elements, fills forms, and submits data
- Takes full-page and element-level screenshots in PNG format
- Evaluates JavaScript in the browser context and retrieves results
- Captures network events, console logs, and DOM snapshots

## Architecture Overview
Chromedp communicates with the browser over a WebSocket connection using the Chrome DevTools Protocol. It manages browser process lifecycle (launching, connecting, and closing), creates browser contexts and tabs, and translates high-level actions into sequences of CDP commands. Everything runs in-process as a Go library with no CGo or external binary dependencies.

## Self-Hosting & Configuration
- Add to your Go project with `go get github.com/chromedp/chromedp`
- Requires Chrome or Chromium installed on the host (or use a headless Docker image)
- Configure browser launch flags via chromedp.Flag options (headless, proxy, window size)
- Use chromedp.NewRemoteAllocator to connect to an existing browser or remote debugging port
- Set timeouts and contexts using standard Go context.Context patterns

## Key Features
- Zero external dependencies beyond Chrome/Chromium itself
- Composable action API chains multiple browser operations in a single Run call
- Full CDP access for advanced use cases (network interception, performance tracing)
- Headless and headed modes for testing and debugging
- Supports concurrent browser contexts for parallel scraping or testing

## Comparison with Similar Tools
- **Selenium** — Requires WebDriver binaries and language bindings; chromedp is a single Go import
- **Puppeteer** — Node.js CDP library; chromedp brings the same concept to Go
- **Playwright** — Multi-browser automation in JS/Python; chromedp is Go-native and Chrome-focused
- **Rod** — Another Go CDP library with auto-download; chromedp has a larger community
- **Colly** — Go web scraping framework using HTTP; chromedp renders JavaScript pages

## FAQ
**Q: Does chromedp work in headless mode?**
A: Yes. By default, chromedp launches Chrome in headless mode. You can switch to headed mode for debugging.

**Q: Can I use chromedp for end-to-end testing?**
A: Yes. Many teams use chromedp for browser-based integration tests in Go projects.

**Q: Does chromedp support file downloads?**
A: Yes. You can configure the download directory and intercept download events via CDP.

**Q: Is chromedp compatible with Docker?**
A: Yes. Use a headless Chrome Docker image and connect chromedp via the remote debugging port.

## Sources
- https://github.com/chromedp/chromedp
- https://pkg.go.dev/github.com/chromedp/chromedp

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Author: AI Open Source