# Headless Chromium Headless Chromium is a library for running Chromium in a headless/server environment. Expected use cases include loading web pages, extracting metadata (e.g., the DOM) and generating bitmaps from page contents -- using all the modern web platform features provided by Chromium and Blink. ## Headless shell The headless shell is a sample application which demonstrates the use of the headless API. To run it, first open the build configuration editor: ``` $ gn args out/Release ``` and enable headless mode with `is_headless = true`. Then build the shell: ``` $ ninja -C out/Release headless_shell ``` After the build completes, the headless shell can be run with the following command: ``` $ out/Release/headless_shell https://www.google.com ``` To attach a [DevTools](https://developer.chrome.com/devtools) debugger to the shell, start it with an argument specifying the debugging port: ``` $ out/Release/headless_shell --remote-debugging-port=9222 https://youtube.com ``` Then navigate to `http://127.0.0.1:9222` with your browser. ## Embedder API The embedder API allows developers to integrate the headless library into their application. The API provides default implementations for low level adaptation points such as networking and the run loop. The main embedder API classes are: - `HeadlessBrowser::Options::Builder` - Defines the embedding options, e.g.: - `SetMessagePump` - Replaces the default base message pump. See `base::MessagePump`. - `SetProxyServer` - Configures an HTTP/HTTPS proxy server to be used for accessing the network. ## Client API The headless client API is used to drive the browser and interact with loaded web pages. Its main classes are: - `HeadlessBrowser` - Represents the global headless browser instance. - `HeadlessWebContents` - Represents a single "tab" within the browser.