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This is a playground to test code. It runs a full Node.js environment and already has all of npm’s 400,000 packages pre-installed, including hypothesis with all npm packages installed. Try it out:

var hypothesis = require("hypothesis")

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hypothesis v1.151.0

Annotate with anyone, anywhere.

Hypothesis client

Build status npm version IRC channel BSD licensed

The Hypothesis client is a browser-based tool for making annotations on web pages. It’s a client for the Hypothesis web annotation service. It’s used by the Hypothesis browser extension, and can also be embedded directly into web pages.

Screenshot of Hypothesis client


See the client Development Guide for instructions on building, testing and contributing to the client.


Join us on Slack - request an invite or log in once you've already created an account - or in on freenode for discussion.

If you'd like to contribute to the project, you should consider subscribing to the development mailing list, where we can help you plan your contributions.

Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms.


The Hypothesis client is released under the 2-Clause BSD License, sometimes referred to as the "Simplified BSD License". Some third-party components are included. They are subject to their own licenses. All of the license information can be found in the included LICENSE file.


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