Servo, the Parallel Browser Engine Project

Servo is a modern, high-performance browser engine designed for both application and embedded use.

Sponsored by Mozilla and written in the new systems programming language Rust, the Servo project aims to achieve better parallelism, security, modularity, and performance.

Download Servo nightly build rendered with Servo This page rendered with Servo on 12 Dec. 2018

Created by Mozilla Research, the Servo project is being built by a global community, from individual contributors to companies such as Mozilla and Samsung.

Servo currently supports Linux, macOS, Windows, and UWP.

Getting Started


You can find what you need to install on your particular system on our GitHub page.


Servo is built with Cargo, the Rust package manager. We also use Mozilla's Mach tools to orchestrate the build and other tasks.

Normal build

To build Servo in development mode. This is useful for development, but the resulting binary is very slow.

git clone
cd servo
./mach build --dev
./mach run tests/html/about-mozilla.html

For benchmarking, performance testing, or real-world use, add the --release flag to create an optimized build:

./mach build --release
./mach run --release tests/html/about-mozilla.html


Use ./mach run [url] to run Servo.

Commandline Arguments

  • -p INTERVAL turns on the profiler and dumps info to the console every INTERVAL seconds
  • -s SIZE sets the tile size for painting; defaults to 512
  • -z disables all graphical output; useful for running JS / layout tests


The Servo Project encourages contributions from experienced and new developers alike. Look at the links at the bottom of the page to learn more and join hundreds of contributors worldwide working to help make Servo even better.

Contributions to Servo or its dependencies should be made in the form of GitHub pull requests. Each pull request will be reviewed by a core contributor (someone with permission to land patches) and either landed in the main tree or given feedback for changes that would be required. All contributions should follow this format, even those from core contributors.

Should you wish to work on an issue, please claim it first by commenting on the GitHub issue that you want to work on it. This is to prevent duplicated efforts from contributors on the same issue.

If you're looking for easy bugs, have a look at the E-Easy issue tag on GitHub.

See for more information on how to start working on Servo.

Pull Request Checklist

  • Branch from the master branch and, if needed, rebase to the current master branch before submitting your pull request. If it doesn't merge cleanly with master you may be asked to rebase your changes.
  • Don't put submodule updates in your pull request unless they are to landed commits.
  • If your patch is not getting reviewed or you need a specific person to review it, you can @-reply a reviewer asking for a review in the pull request or a comment, or you can ask for a review in the Servo room on the Mozilla Matrix.
  • Add tests relevant to the fixed bug or new feature. For a DOM change this will usually be a web platform test; for layout, a reftest. See our testing guide for more information.
  • For specific git instructions, see GitHub workflow 101.
Start Contributing


Servo contributors frequent the Servo room on the Mozilla Matrix. You can also join the dev-servo mailing list.


We follow the Rust Code of Conduct.