HypoFuzz
An advanced fuzzing backend, and dashboard, for your Hypothesis tests.
Built with care by the Hypothesis maintainers.
Find more bugs, without more tests
HypoFuzz uses advanced techniques inspired by the fuzzing literature to find deeply hidden bugs—just by running your existing Hypothesis tests.
You give HypoFuzz CPU time, and HypoFuzz gives you bugs. We think that's a pretty good trade!
Understand your test effectiveness
How confident are you in your test suite? The HypoFuzz dashboard shows you what your Hypothesis tests do—and don't—cover.
You test your code. HypoFuzz can test your tests.
Put your idle compute to work
HypoFuzz scales efficiently with your available CPU cores.
Workers are designed to come and go, and can be stopped or started alongside availability and demand.
- Only have one shared CI machine? No problem; run HypoFuzz during the quieter hours.
- Have an entire fleet? Allocate idle workers as they become available.
Free for non-commercial use
We love (and started from) research and open source. Any non-commercial use of HypoFuzz is completely free.
Get started 
Not only that, we'd be delighted to chat or offer advice – reach out to us!
Built by the Hypothesis maintainers, with care
We love testing. Hypothesis is (and always will be) open-source, because we love making high-quality tooling available to everyone.
We built HypoFuzz because we saw an opportunity to extend Python's world-leading property-based testing library, and provide even better testing tools for businesses.
HypoFuzz Newsletter
We'll have plenty to share as we roll out new features! The first place you'll hear about them is our low-volume newsletter.