Buildbot is a free, open-source continuous integration framework written in Python and Twisted. Configure builds as code and self-host masters and workers.
Category
DevOps
Pricing
Free (open source), from Free
Verified
Not yet
Last updated
July 18, 2026
Founded
2003
APIOpen SourceSelf-Hosted
Overview
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.
Key Features
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.
Pricing
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.
Key Features
Python-based configuration — Build logic is defined as Python code rather than a YAML file, enabling full programmatic control.
Master/worker architecture — Distributed masters coordinate work while workers execute build and test jobs across machines.
Version control integrations — Polls or receives webhooks from Git and Subversion to trigger builds on code changes.
Parallel, cross-platform execution — Runs jobs in parallel across machines and operating systems.
Extensive status reporting — Web UI and external notification support for build results.
Fully self-hosted — No vendor lock-in; runs entirely on infrastructure you control.
Pros & Cons
Pros
Completely free and open source with no licensing fees
Maximum configuration flexibility via Python code
Proven at scale by projects like Chromium, Mozilla, and CPython
Works across all major operating systems
Cons
Requires Python coding knowledge to configure, a steeper learning curve than YAML-based tools
No managed or hosted offering; infrastructure must be self-managed
Teams are responsible for their own scaling and uptime
More dated UI compared to modern CI SaaS platforms
Pricing
Self-Hosted Free N/A
Frequently Asked Questions
Is Buildbot free?
Yes, Buildbot is free, open-source software licensed under GPLv2.
Do I need to know Python to use Buildbot?
Yes, Buildbot's entire configuration is written as Python code rather than a YAML file.
Does Buildbot offer a hosted or cloud version?
No, Buildbot is self-hosted only; there is no official managed cloud offering.
What is Buildbot's master/worker architecture?
Masters schedule and coordinate build jobs, while workers execute the actual build and test tasks, potentially across many machines.
Which major projects use Buildbot?
Buildbot has been used by Chromium, WebKit, Mozilla, and the Python language's own CPython project, among others.
How does Buildbot compare to Jenkins?
Both are free and self-hosted, but Buildbot configures pipelines as Python code, while Jenkins typically uses a UI or Groovy-based pipeline scripts.