Best Web Annotation Tools
The best web annotation tools for highlighting, noting, and remembering
Highlight, note, and remember
Reading on the web is passive until you engage with the content. Annotations turn passive reading into active research. We tested the top web annotation tools to find which ones make highlighting, noting, and rediscovering information seamless.
What to look for
Our picks
Backdrop
Built-in annotation system that works on archived pages. Highlight text in yellow, blue, green, or rose. Add notes to any highlight. Annotations are searchable and persist permanently within your archive.
Pros
- Annotations persist permanently on archives
- Four highlight colors for categorization
- Searchable annotations
- Works on any archived format
Cons
- Only works on archived pages, not live web
- Free tier limited to 100 archives
- No collaborative annotation yet
Hypothesis
An open-source web annotation tool that works on live web pages. Annotate any page on the web, create public or private annotations, and join group discussions. Widely used in education and research.
Pros
- Annotate any live web page
- Open source and free
- Group annotation and discussion
- Used in classrooms and research
Cons
- No permanent page archiving
- Annotations lost if page changes
- Requires browser extension
- Public by default
Diigo
A veteran web annotation and bookmarking tool. Highlight and sticky-note any web page. Organize annotations with tags. Supports both web and PDF annotation. Social features for group research.
Pros
- Highlight and sticky notes on any page
- Annotation organization with tags
- PDF annotation support
- Group research features
Cons
- Dated interface
- Free tier limited features
- No permanent archiving
- Browser extension can be buggy
Glasp
A modern web annotation tool with a YouTube-focused feature set. Highlights, notes, and organizes content. Supports AI-powered summaries of highlighted content. Social features for sharing highlights.
Pros
- Clean, modern interface
- YouTube transcript highlighting
- AI summary of highlights
- Community features
Cons
- Smaller user base
- No PDF annotation
- Limited organization features
- No permanent archiving
Memex
A browser extension for annotating and organizing web research. Highlights, bookmarks, and notes on any page. Full-text search across your annotations. Built for researchers and knowledge workers.
Pros
- Highlight and annotate any page
- Full-text search across annotations
- Side-by-side annotation view
- Bookmark with notes
Cons
- Browser extension only
- No mobile support
- Limited organization features
- No permanent archiving of pages
Highlight what matters
Backdrop's annotation system makes every highlight permanent and searchable. Capture your thoughts alongside the content they reference.
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