Most web annotations disappear. These ones don't.

Last updated June 2026

You highlight a paragraph on a web article. You leave a comment on a competitor's website. You flag a UI issue on your staging site. Where does that annotation go?

In most tools, the annotation lives in the annotation tool. Disconnected from your notes. Disconnected from your research. Disconnected from the project it's about. You forget you made it. It becomes unfindable within weeks.

Website annotation tools range from academic collaboration platforms to bug reporting tools to personal highlighting extensions. The right one depends on what you're annotating, who you're annotating for, and whether the annotation needs to exist beyond this moment.

Quick comparison

Fabric

Fabric's annotate the web feature works differently from every other tool on this list. Most tools create a separate annotation layer that lives inside the annotation tool. Fabric creates annotations that become part of your searchable knowledge library.

How it works: The browser extension lets you highlight text, annotate images, and leave comments anchored to specific elements on any web page. Annotations persist across browser sessions, device switches, and page reloads. They stay exactly where you left them the next time you visit.

What makes it different: Six months later, when you're researching a related topic, the AI assistant can find that annotation. Semantic search surfaces your web annotations alongside your notes, saved articles, PDFs, and meeting recordings. The annotation isn't trapped in an annotation tool. It's part of your knowledge.

Shared annotations let collaborators see your highlights and comments in context with threaded replies. Private by default. Sharing is opt-in.

Beyond web annotation: Fabric also annotates PDFs, markdown files, notes, JSON files, and other documents with the same highlight-and-comment model. Everything is searchable, everything is accessible to the AI, everything connects to the rest of your library. Quick capture saves web pages with full content extraction into your library alongside annotations.

Limitations: No public annotation layer (Hypothesis and Glasp let annotations be visible to other users on the same page). No LMS integration for graded academic assignments. No bug reporting workflow with ticket creation. Fabric is for personal and team knowledge annotation, not for public social annotation or development QA.

Best for: Researchers, students, writers, and knowledge workers who annotate the web as part of a broader research and thinking workflow. People who want their web annotations to be findable alongside everything else they've saved. People who annotate articles, competitor sites, and reference material and need it all searchable by meaning months later.

Academic and social annotation

Hypothesis

Hypothesis is the standard for academic social annotation. Students and educators annotate web pages, PDFs, and ePubs collaboratively, with annotation layers visible to groups, classes, or the public. LMS integration with Canvas, Blackboard, and others lets instructors create graded annotation assignments.

Strengths: Open source. Free for personal use. Group and public annotation layers. LMS integration for graded assignments. Institutional pricing from ~$4/user/year. Annotate web pages, PDFs, and ePubs. Threaded replies on annotations. The most established academic annotation tool, used by hundreds of institutions. Active development (updated June 2026).

Limitations: No AI. No connection to your broader knowledge base. Annotations live in Hypothesis only. No personal knowledge management. Interface can feel dated. Chrome Web Store rating is mixed (2.9 stars). Desktop/browser only (no mobile app).

Best for: Higher education. Students annotating assigned readings collaboratively. Instructors guiding close reading with pre-placed annotations. Academic research groups sharing annotations on papers. Not for personal knowledge management.

Liner

Liner is a web highlighting tool for students and readers. Highlight text on any web page. Organise highlights by topic. AI generates summaries of your highlighted content. Clean, modern interface.

Strengths: Clean highlighting experience. Sync across devices. AI-powered summaries of highlighted content. Chrome, Safari, iOS, Android. Organised by topic with search. Popular with students.

Limitations: No collaborative annotation (highlights are personal). No threaded comments. No document or PDF annotation. Premium required for unlimited highlights and AI (~$8-10/month). No connection to a broader knowledge workspace. Highlights live in Liner only.

Best for: Students and individual readers who highlight web articles and want AI summaries of their highlights.

Glasp

Glasp is a social highlighting tool where your highlights are public by default. The idea: build a public knowledge graph of highlighted passages across the web. Other users can see what you've highlighted on the same articles.

Strengths: Free. Public highlights create serendipitous connections with other readers. AI summary of your highlights. Export to Obsidian, Notion, Readwise. Community of highlight-sharers.

Limitations: Public by default (a feature for some, a dealbreaker for others). No private annotations on the free tier. No threaded comments. No PDF or document annotation. No connection to a broader workspace. The social model requires comfort with public visibility.

Best for: Readers who want to share what they're highlighting publicly and discover what others highlight on the same content.

Diigo

Diigo is the veteran social bookmarking and annotation tool. Save pages, highlight text, add sticky notes, tag and organise. Archived pages preserve content even if the original goes down.

Strengths: Bookmarking + annotation in one tool. Archived pages survive link rot. Groups for sharing annotated collections. Tags and lists for organisation. Free tier available. Has been around since 2006.

Limitations: Interface feels dated. Free tier has ads. No AI. No semantic search. No connection to a broader knowledge workspace. Annotations live in Diigo only. Limited collaboration compared to Hypothesis.

Best for: Researchers who want to bookmark, annotate, and archive web pages for long-term reference. The veteran's choice.

Bug reporting and visual feedback

Marker.io

Marker.io is for development teams. Click a button on your website, annotate the screenshot with arrows, text, and highlights, and the annotation automatically creates a bug ticket in Jira, Linear, Asana, Trello, GitHub, or GitLab. Console logs, environment info, and metadata are captured automatically.

Strengths: One-click bug reporting from live websites. Automatic ticket creation in your project management tool. Console logs and environment data captured with each report. Screen recording. Widget embeds on your site for client feedback. From ~$39/month.

Limitations: Not a knowledge tool. Annotations create tickets, they don't build a searchable library. For QA and bug reporting specifically. Pricing starts at $39/month.

Best for: Development teams who need bug reporting from live websites with automatic ticket creation. Client feedback on staging sites. QA workflows.

How to choose

If your web annotations need to connect to your research and knowledge: Fabric. Annotations are searchable alongside your entire library. The AI can find and summarise them months later. Part of a workspace, not a standalone extension.

If you need collaborative academic annotation: Hypothesis. LMS integration. Group and public layers. The academic standard.

If you want to highlight articles with AI summaries: Liner. Clean, modern, student-focused.

If you want to share highlights publicly: Glasp. Free. Social. Public by default.

If you want to bookmark, annotate, and archive: Diigo. The veteran. Archived pages survive link rot.

If you need bug reporting from websites: Marker.io. Annotations become tickets automatically.

What makes web annotation actually useful long-term

Most web annotations are write-once, read-never. You highlight a paragraph. You feel productive. You never find that highlight again because it's trapped in a browser extension you don't search.

The annotation tools that matter long-term are the ones where your annotations are findable when you need them, not just when you make them. That means searchable, connected, and accessible to the AI you use to think with.

Fabric is the only tool on this list where web annotations are indexed by semantic search, accessible to an AI assistant across your full library, and connected to your notes, files, recordings, and saved content. The highlight you made in January becomes the evidence the AI cites in June.

Every other tool on this list stores annotations in a separate silo. That silo is useful at the moment of annotation. It stops being useful the moment you forget it exists.

FAQs

Which is free? Hypothesis (personal use). Glasp (free, public by default). Diigo (free tier with ads). Fabric (generous free plan). Liner (free with limits).

Which works on mobile? Liner (iOS, Android). Fabric (iOS, Android). Glasp (mobile web). Hypothesis and Diigo are browser-extension-based (desktop).

Can any of these annotate PDFs too? Fabric annotates PDFs, documents, notes, and web pages. Hypothesis annotates web pages, PDFs, and ePubs. Diigo annotates web pages only. Liner and Glasp are web highlighting only.

Which connects annotations to my notes and files? Only Fabric. Every other tool stores annotations in its own silo. In Fabric, web annotations are part of the same library as your notes, files, meeting recordings, and research. All searchable. All AI-accessible.

Which has AI? Fabric (full AI assistant across your entire library, including annotations). Liner (AI summaries of highlights). Glasp (AI summary). Hypothesis, Diigo, and Marker.io have no AI.

Can I collaborate on web annotations? Hypothesis (group and public layers, threaded replies, LMS grading). Fabric (shared annotations with threaded replies, private by default). Glasp (public highlights visible to all users). Diigo (groups). Liner and Marker.io are individual or team-based without annotation-layer collaboration.

Which is best for academic research? Hypothesis for collaborative close reading with classmates and instructors in an LMS. Fabric for personal research where web annotations need to connect to your papers, notes, and broader literature review.