Chromium Embedded Framework vs. Raw Chromium Content API

This article explores the Chromium Embedded Framework (CEF), an open-source framework designed for embedding a Chromium-based web browser into third-party applications. It also provides a direct comparison between using CEF's stable C and C++ APIs versus integrating the raw Chromium Content API directly, highlighting key differences in API stability, build complexity, compiler requirements, and feature availability.

What is the Chromium Embedded Framework?

The Chromium Embedded Framework (CEF) is an open-source software framework used to embed a full-featured HTML5 web browser control into desktop and standalone applications. Founded in 2008, CEF sits on top of the Google Chromium project.

It packages the underlying Blink rendering engine and V8 JavaScript engine into a manageable library. CEF is widely used in commercial and open-source software to render user interfaces using web technologies or to display web content natively within a host application.

What is the Raw Chromium Content API?

The Chromium Content API is the internal architectural layer within the Chromium project that provides the core multi-process code needed to render a page using the Blink engine. It abstracts the sandbox, GPU acceleration, and network stacks, leaving out the specific Google Chrome browser features like extensions, autofill, and spelling correction. While it is possible to build an application directly on top of the Content API, it was primarily designed for Chromium's own internal use rather than for third-party developers.

Key Differences: CEF API vs. Raw Content API

Choosing between CEF and the raw Chromium Content API comes down to how your application interacts with the underlying browser engine. Below are the core technical differences between the two approaches.

1. C/C++ Architecture and Compiler Freedom

  • Raw Content API: The Content API is written entirely in C++. Because C++ lacks a standardized Application Binary Interface (ABI), using the Content API requires your entire application to be compiled with the exact same compiler, flags, and C++ standard library (typically Clang and libc++) that Chromium uses.
  • CEF C and C++ APIs: CEF solves the C++ ABI problem by exposing a base C API (libcef). Because C has a stable ABI, CEF separates the Chromium internals from your application's build environment. On top of this C API, CEF provides a C++ wrapper (libcef_dll_wrapper) that translates C structures back into easy-to-use C++ classes. Your application links against the C++ wrapper using your preferred compiler (such as MSVC or GCC), while the wrapper communicates safely with the pre-compiled CEF binaries via the C API. This C layer also makes it easy to generate bindings for other languages like C#, Python, and Java.

2. API Stability and Maintenance

  • Raw Content API: Chromium moves fast, and the Content API makes no guarantees regarding backward compatibility. Interfaces, classes, and methods change or disappear with every Chromium milestone release. Developers using the Content API must constantly rewrite their integration code to keep up with security updates.
  • CEF API: A primary goal of CEF is to insulate developers from Chromium's constant internal refactoring. While CEF updates its underlying Chromium version regularly, the CEF C and C++ APIs remain relatively stable. Updating to a newer version of CEF usually requires minimal changes to the host application's codebase.

3. Build System and Distribution

  • Raw Content API: There are no official pre-built binaries for the Content API. To use it, you must download the entire Chromium source tree (over 30 GB of data) and build it yourself using Google’s custom toolchain (depot_tools, GN, and Ninja). This requires a high-end machine with significant RAM and takes hours to compile.
  • CEF API: CEF provides automated, pre-built binary distributions for Windows, macOS, and Linux. You can download a relatively small SDK package, link it to your existing project using standard build systems like CMake, and start developing immediately without ever compiling Chromium from source.

4. Out-of-the-Box Features

  • Raw Content API: The Content API only handles the bare minimum required to render a webpage. It does not include basic browser features like printing, PDF viewing, file download management, JavaScript dialogs, or context menus. If you use the Content API, you must implement all of these features from scratch.
  • CEF API: CEF sits between the Content API and a full browser, meaning the CEF developers have already implemented these missing pieces. CEF provides built-in handlers for printing, PDF generation, custom network schemes, proxy resolution, and windowless (off-screen) rendering right out of the box.

5. Inter-Process Communication (IPC)

  • Raw Content API: Chromium uses a strict multi-process architecture. Using the Content API requires you to manually write complex Mojo IPC interfaces to pass data between the main Browser process and the sandboxed Renderer processes.
  • CEF API: CEF abstracts Chromium's Mojo IPC system into a much simpler messaging API. It provides straightforward C++ classes (such as CefProcessMessage) to send asynchronous data and bind JavaScript variables between the host application and the V8 engine running in the renderer process.