Chromium is a free and open-source web browser project, primarily developed and maintained by Google. It is a widely used codebase, providing the vast majority of code for Google Chrome and many other browsers, including Microsoft Edge, Samsung Internet, and Opera. The code is also used by several app frameworks.

Chromium is a free and open-source software project. The Google-authored portion is shared under the 3-clause BSD license. Third party dependencies are subject to a variety of licenses, including MIT, LGPL, Ms-PL, and an MPL/GPL/LGPL tri-license.

This licensing permits any party to build the codebase and share the resulting browser executable with the Chromium name and logo. Thus many Linux distributions do this, as well as FreeBSD and OpenBSD.

Chromium provides the vast majority of source code for Google Chrome, but there are important differences.

Chromium lacks the following Chrome features:

Google first chose the name "Chrome" for its browser. Then the open-source release was named "Chromium" because chromium metal is used to make chrome plating.

Chrome has the same user interface functionality as Chromium, but with a Google-branded color scheme. Unlike Chromium, Chrome is not open-source; its binaries are licensed as freeware under the Google Chrome Terms of Service.

The Chromium browser codebase contains over 36 million source lines of code, excluding comments and blank lines.