The Web, Annotated.

We’re happy to announce the first version of our application. It’s an annotator that you can carry around the web with you. Just click the install button below to try it in your browser. We’ve written a little about what it’s capable of now, what it’s not, and where we’re headed.

Launch Hypothesis

Drag the button into your bookmarks bar then click it to launch the Hypothesis application.

We’re currently hard at work on a FireFox extension. We also support other browsers.

Launch Hypothesis

Drag the button into your bookmarks bar then click it to launch the Hypothesis application.

Are you a Chrome user? We have an extension for you.

Installation options:

for Chrome: Add to Chrome
for Firefox: Launch Hypothesis
for Safari, IE and Opera: Launch Hypothesis

Drag the button to your bookmark bar, use on any page to open Hypothesis.

Now, drop the button into your bookmarks bar.


  • Annotating

    Easily highlight and annotate web pages and online PDFs. Your annotations will be saved and loaded whenever you return to the document even if the content has been updated.

  • Commenting

    Hold conversations directly on the web by commenting and replying on annotations.

  • Tagging

    Tags allow you to structure and organize your annotations across multiple documents. Click on a tag or use the search bar to find all annotations with a specific tag.

  • Sharing

    We give every annotation its own url allowing them to quickly and easily be shared with others.

  • Privacy Controls

    All annotations can be marked as public or “Only Me” giving you control over who can see what you say.

Our roadmap will give you an idea of what’s coming up in the near future.

The Hypothesis sidebar extension

About us

We are a non-profit organization, funded through the generosity of the Knight, Mellon, Shuttleworth and Sloan Foundations and through the support of individuals like yourself.

  • We publish regular updates through Twitter.
  • All of our code is open-source and available on GitHub.
  • Our blog keeps track of our progress and thinking.

Read more about Hypothesis

Recent News

  • Annotations at the W3C

    For a while now, a dedicated group of individuals has been working towards a web annotation standard-- the idea being that annotation is something that will...

    Read more…

  • Launch!

    As of today, we're making our general purpose annotator available from our homepage. If you use the Chrome browser, you can download and install it as an extens...

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  • Open Annotation RDFa using JSON

    The Open Annotation Core Data Model is something we're keen to include in future releases. We're exploring using it via JSON-LD natively in Annotato...

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  • Supporting Open Annotation

    In its mission to connect the world’s knowledge and thoughts, the solution pursues is a web-wide mechanism to create, share and discover annotati...

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