The collaborative annotation layer for the open web.
Annotator is an open-source JavaScript library for adding annotation functionality to web content: highlights, notes, metadata, storage, and shared discussion directly on top of documents.
This project is being actively rebooted. The historical library, docs, and site content have been consolidated into one repository so the code, public site, and documentation can evolve together.
Turn any web page into an annotatable surface with highlights, comments, metadata, and UI components for creating and viewing annotations.
Browser-side UI and selection logic combined with pluggable identity, authorization, and storage modules.
There are still not many mature open-source annotation stacks. Annotator remains a credible base for revival.
Modern local build restored, tests running in headless Chrome, docs and site consolidated into the main repository.
Why Annotator Still Matters
A library, not just a demo
Annotator was used in real projects across education, publishing, research, and public knowledge. It was built around a clean separation between browser UI, annotation storage, and identity/authz concerns, which still makes architectural sense today.
The reboot is not about preserving a relic. It is about recovering a serious open-source annotation system and putting it back on a maintainable footing.
Technical docs
Installation, usage, modules, API reference, roadmap, and change history.
Showcase
See projects and organizations that historically used Annotator in the wild.
Plugins
Browse the historical plugin catalog for integrations, storage backends, and UI extensions.
News and notes
Historical community updates, call notes, and project conversations imported from the old site.
Flowershow