The Open-Source License Behind the Chromium Web Browser

This article provides a direct overview of the licensing structure for the Chromium web browser. It identifies the primary open-source license governing the majority of Chromium's original source code, explains the rules of this license, and clarifies how it allows other companies to build their own software using the browser's foundation.

The majority of the original source code for the Chromium web browser is distributed under the 3-Clause BSD License (also known as the New BSD License or Modified BSD License). All original code written specifically for the project by the Chromium authors is released under this terms of this agreement.

The 3-Clause BSD License is a permissive open-source software license. Unlike "copyleft" licenses—which require any modified versions of the software to also be released as open-source—the BSD license places very few restrictions on what developers can do with the code. It allows anyone to freely use, modify, and redistribute the Chromium source code for both open-source and proprietary, commercial purposes.

To comply with the 3-Clause BSD License, developers using Chromium's original code must only follow three simple conditions:

  1. Source Code Redistribution: If the code is redistributed in its source form, it must retain the original copyright notice, the list of conditions, and the disclaimer of warranty.
  2. Binary Redistribution: If the code is compiled and distributed as a binary (an executable program), the documentation or materials provided with the distribution must reproduce the original copyright notice, the list of conditions, and the disclaimer.
  3. No Endorsement: Neither the name of the copyright holder (Google Inc. and the Chromium authors) nor the names of its contributors may be used to endorse or promote products derived from the software without specific prior written permission.

Because the 3-Clause BSD License is so permissive, major technology companies can use Chromium as the foundation for their own web browsers, add proprietary features, and distribute the final product under their own terms. This is the exact mechanism that allows Google to build Google Chrome, Microsoft to build Microsoft Edge, and other companies to build browsers like Brave, Opera, and Vivaldi without being forced to release their proprietary additions to the public.

While the original code written by the Chromium team is strictly governed by the 3-Clause BSD License, it is worth noting that the complete Chromium project relies on several third-party libraries to function. Consequently, the fully compiled browser contains components governed by other open-source licenses, including the MIT License, the Apache 2.0 License, the Mozilla Public License (MPL), and the GNU Lesser General Public License (LGPL). However, the core original codebase remains defined by the 3-Clause BSD License.