Buildbot is a free, open-source continuous integration framework written in Python and Twisted. Configure builds as code and self-host masters and workers.
Researched and fact-checked by Bartu Cavusoglu · Updated July 18, 2026
Buildbot is a free, open-source continuous integration framework first released in April 2003 by Brian Warner as a lightweight alternative to Mozilla's Tinderbox. It is licensed under GPLv2 and maintained today by Dustin J. Mitchell and a community of contributors.
Buildbot was originally built to automate builds and tests for the Twisted Python library, and later grew into a general-purpose CI framework adopted by projects including Chromium, WebKit, Mozilla, and CPython.
Unlike YAML-based CI tools, Buildbot's entire configuration is written in Python code, giving teams full programmatic control over build logic. It uses a master/worker architecture for distributed, parallel job execution, integrates with Git and Subversion, and provides a web UI for status reporting.
Buildbot is entirely free and open source under the GNU General Public License v2.0, with no managed hosting or paid tiers. Teams run and maintain their own masters and workers on their own infrastructure.
Yes, Buildbot is free, open-source software licensed under GPLv2.
Yes, Buildbot's entire configuration is written as Python code rather than a YAML file.
No, Buildbot is self-hosted only; there is no official managed cloud offering.
Masters schedule and coordinate build jobs, while workers execute the actual build and test tasks, potentially across many machines.
Buildbot has been used by Chromium, WebKit, Mozilla, and the Python language's own CPython project, among others.
Both are free and self-hosted, but Buildbot configures pipelines as Python code, while Jenkins typically uses a UI or Groovy-based pipeline scripts.