|Initial release||2 September 2008|
|Operating system||Windows, Linux, Android, iOS, macOS, BSDs|
|Platform||IA-32, x86-64, ARM, ARM64|
|License||BSD-3 and others|
Chromium is a free and open-source web browser project, mainly developed and maintained by Google. This codebase provides the vast majority of code for the Google Chrome browser, which is proprietary software and has some additional features.
The Chromium codebase is widely used. Microsoft Edge, Samsung Internet, Opera, and many other browsers are based on the Chromium code. Moreover, significant portions of the code are used by several app frameworks.
Google does not provide an official stable version of the Chromium browser, but does provide official API keys for some features, such as speech to text and translation.
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, so the name "Chromium" was chosen by Google because chromium metal is used in chrome plating.
Chromium lacks the following Chrome features:
While Chrome has the same user interface functionality as Chromium, it changes the color scheme to the Google-branded one. Unlike Chromium, Chrome is not open-source, so its binaries are licensed as freeware under the Google Chrome Terms of Service.
The Chromium browser codebase contains about 35 million source lines of code.
Chromium has been a Google project since its inception, and Google employees have done the bulk of the development work.
Google refers to this project and the offshoot ChromiumOS as "the Chromium projects", and its employees use @chromium.org email addresses for this development work. However, in terms of governance, the Chromium projects are not independent entities; Google retains firm control of them.
The Chromium browser codebase is widely used, so others have made important contributions, most notably Microsoft, Igalia, Yandex, Intel, Samsung, LG, Opera, and Brave. Some employees of these companies also have @chromium.org email addresses.
C++ is the primary language, comprising about half of the codebase. This includes the Blink and V8 engines, the implementation of HTTP and other protocols, the internal caching system, and other essential browser components.
About 10% of the codebase is written in C. This is mostly from third-party libraries that provide essential functionality, such as SQLite and numerous codecs.
Support for mobile operating systems requires special languages: Java for Android, and for iOS both Swift and Objective-C.
In January 2023, Google announced they will be allowing third-party Rust libraries.
The bug tracking system is a publicly accessible website. Participants are identified by their email addresses.
The Chromium continuous integration system automatically builds and tests the codebase several times a day.
Builds are identified by a four-part version number that is major.minor.build.patch. This versioning scheme and the branch points that occur every six to seven weeks are from Google Chrome and its development cycle.
Google Chrome debuted in September 2008, and along with its release, the Chromium source code was also made available, allowing builds to be constructed from it.
Upon release, Chrome was criticized for storing a user's passwords without the protection of a master password. Google has insisted that a master password provides no real security against knowledgeable hackers, but users argued that it would protect against co-workers or family members borrowing a computer and being able to view stored passwords as plaintext. In December 2009, Chromium developer P. Kasting stated: "A master password was issue 1397. That issue is closed. We will not implement a master password. Not now, not ever. Arguing for it won't make it happen. 'A bunch of people would like it' won't make it happen. Our design decisions are not democratic. You cannot always have what you want."
Version 6 introduced features for user interface minimalism, as one of Google's goals was to make the browser "feel lightweight (cognitively and physically) and fast". The changes were a unified tools menu, no home button by default (although user configurable), a combined reload/stop button, and the bookmark bar deactivated by default. It also introduced an integrated PDF reader, WebM and VP8 support for use with HTML5 video, and a smarter URL bar.
Version 7 boosted HTML5 performance to twice that of prior versions via hardware acceleration.
Version 8 focused on improved integration into ChromeOS and improved cloud features. These include background web applications, host remoting (allowing users centrally to control features and settings on other computers) and cloud printing.
Version 9 introduced a URL bar feature for exposing phishing attacks, plus sandboxing for the Adobe Flash plug-in. Other additions were the WebGL library and access for the new Chrome Web Store.
In February, Google announced that it was considering large-scale user interface (UI) changes, including at least partial elimination of the URL bar, which had been a mainstay of browsers since the early years of the Web. The proposed UI was to be a consolidation of the row of tabs and the row of navigation buttons, the menu, and URL bar into a single row. The justification was freeing up more screen space for web page content. Google acknowledged that this would result in URLs not always being visible to the user, that navigation controls and menus may lose their context, and that the resulting single line could be quite crowded. However, by August, Google decided that these changes were too risky and shelved the idea.
In March, Google announced other directions for the project. Development priorities focused on reducing the size of the executable, integrating web applications and plug-ins, cloud computing, and touch interface support. Thus a multi-profile button was introduced to the UI, allowing users to log into multiple Google and other accounts in the same browser instance. Other additions were malware detection and support for hardware-accelerated CSS transforms.
By May, the results of Google's attempts to reduce the file size of Chromium were already being noted. Much of the early work in this area concentrated on shrinking the size of WebKit, the image resizer, and the Android build system. Subsequent work introduced a more compact mobile version that reduced the vertical space of the UI.
Other changes in 2011 were GPU acceleration on all pages, adding support for the new Web Audio API, and the Google Native Client (NaCl) which permits native code supplied by third parties as platform-neutral binaries to be securely executed within the browser itself. Google's Skia graphics library was also made available for all Chromium versions.
The sync service added for Google Chrome in 2012 could also be used by Chromium builds. The same year, a new API for high-quality video and audio communication was added, enabling web applications to access the user's webcam and microphone after asking permission to do so. Then GPU accelerated video decoding for Windows and support for the QUIC protocol were added.
In 2013, Chromium's modified WebKit rendering engine was officially forked as the Blink engine.
Other changes in 2013 were the ability to reset user profiles and new browser extension APIs. Tab indicators for audio and webcam usage were also added, as was automatic blocking of files detected as malware.
Version 69 introduced a new browser theme, as part of the tenth anniversary of Google Chrome. The same year, new measures were added to curtail abusive advertising.
Starting in March 2021, the Google Chrome sync service can no longer be used by Chromium builds.
In addition to Google Chrome, many other notable web browsers have been based on the Chromium code.
Significant portions of the Chromium code are used by some application frameworks. Notable examples are Electron, the Chromium Embedded Framework, and the Qt WebEngine. These frameworks have been used to create many apps.
升级内核至Chromium 45 内核