External contributions to Hypothesis are currently less easy than I would like them to be. You might want to consider any of the following in preference to trying to work on the main Hypothesis code base:

  • Submit bug reports
  • Submit feature requests
  • Write about Hypothesis
  • Build libraries and tools on top of Hypothesis outside the main repo

And indeed I’ll be delighted with you if you do! If you need any help with any of these, get in touch and I’ll be extremely happy to provide it.

However if you really really want to submit code to Hypothesis, the process is as follows:

You must own the copyright to the patch you’re submitting as an individual. I’m not currently clear on how to accept patches from organisations and other legal entities.

If you have not already done so, you must sign a CLA assigning copyright to me. Send an email to with an attached copy of the current version of the CLA and the text in the body “I, (your name), have read the attached CLA and agree to its terms” (you should in fact have actually read it).

Note that it’s important to attach a copy of the CLA because I may change it from time to time as new things come up and this keeps a record of which version of it you agreed to.

Then submit a pull request on Github. This will be checked by Travis and Appveyor to see if the build passes.

Advance warning that passing the build requires:

  1. All the tests to pass, naturally.
  2. Your code to have 100% branch coverage.
  3. Your code to be flake8 clean.
  4. Your code to be a fixed point for a variety of reformatting operations (defined in

It is a fairly strict process.

Once all this has happened I’ll review your patch. I don’t promise to accept it, but I do promise to review it as promptly as I can and to tell you why if I reject it.

Documentation changes

The CLA is still required for significant documentation changes, but if you want to just submit typo fixes and so on I’ll happily just merge them. A CLA request for fixing a typo seems a bit silly.