Chromium

Chromium is a program for browsing the internet, in other words a browser. What’s special about it: the entire blueprint of the program is public. Anyone may download it, read it, modify it, and use it for their own products. Software like this is called open source. The project was started by Google and is still funded mainly by Google today. Google builds its well-known browser Chrome from Chromium by adding a few of its own components. So when people speak of Chromium, they usually mean less a browser to install for yourself and more the shared foundation on which almost all of today’s browsers are built.

When almost all browsers share the same underpinnings

Chromium has become the standard technology of the internet. Chrome, Microsoft Edge, Opera, Brave, and Vivaldi all build on it. Together they account for roughly three quarters of all browser usage worldwide. There are only two serious alternatives left with their own technology: Firefox by Mozilla and Safari by Apple.

This has an unpleasant consequence. If a website works in Chromium, many developers consider their job done. Whether the site also works in Firefox or Safari is often no longer even checked. This effectively means that a single project decides what is technically possible on the web. Critics see this as a concentration of power, similar to Microsoft’s Internet Explorer in the late nineties.

An example of this was provided by the 2024 dispute over Manifest V3. This is a rule change for extensions, i.e. small add-on programs within the browser. It restricts how extensively ad blockers may intervene. Because the change is built into Chromium, it immediately affected almost all browsers at once. Individual providers like Brave had to go to considerable lengths to work around the rule.

Rendering engine, JavaScript, and the boundary with Chrome

A browser has two central components. The rendering engine translates the code of a webpage into a visible image made up of text, images, and buttons. In Chromium, it’s called Blink. The second component executes programs written in the JavaScript language, for example for video players or search suggestions. This part is called V8 and is considered one of the fastest pieces of software of its kind.

The program code sits publicly on Google’s servers. About 90 percent of the changes come from Google employees, with the rest contributed by Microsoft, Intel, Igalia, and individual volunteers. Every change must be reviewed and approved by authorized people. This means Google retains control over the direction of the project, even though in theory anyone may contribute.

Chrome is Chromium plus closed additional components. These include the automatic update function, sign-in with a Google account, playback of copy-protected videos such as on Netflix, and building blocks that send usage data to Google. Anyone who installs pure Chromium therefore gets less convenience, but also less data transmission. This is exactly the dividing line that providers like Brave build on: they take the open core and replace the Google parts with their own.

Chromium in apps, cars, and AI tools

Chromium is found in far more than just browsers. Many desktop programs are, in truth, websites running inside a hidden browser window. This is made possible by a toolkit called Electron, which bundles Chromium. Discord, Slack, Visual Studio Code, and the desktop version of Spotify all work this way. This also explains why such programs often need a surprising amount of memory.

In tech news, Chromium comes up especially in connection with AI. When an AI system independently researches on the web, fills out forms, or compares prices, it usually controls an invisible Chromium instance in the background to do so. Tools like Playwright or Puppeteer are built specifically for this. Google’s own AI features built directly into the browser are also developed in Chromium first.

A common misconception is equating Chromium with Chrome. Chromium is the open blueprint, Chrome is Google’s finished product. It’s similar to how Android relates to smartphones from various manufacturers. And when US courts deliberate on a possible spin-off of Chrome, they are dealing with Google’s product and its market power, not with the open code underneath.