Best Online Highlighters Compared (2026)

Why You Need an Online Highlighter

An online highlighter is a browser tool that lets you mark text on any web page or PDF, attach a note, and find it again later. For most readers the best option is Glasp: it's free, runs on Chrome, Safari, Brave, Edge, and Opera, and turns your highlights into a searchable, shareable knowledge base. If you want something more specialized, the five tools below cover academic groups, AI search, team research, and private minimalists.

Here's the problem every reader knows. You find an incredible insight, close the tab, and never see it again. Bookmarking saves the page, but not the specific passage that mattered. Copy-pasting into a doc works, but it strips the original context and leaves a mess of disconnected snippets.

Highlighters fix this by letting you mark text in place, add your own notes, and organize everything in one spot. The best tools also export your highlights into note-taking apps like Notion, Obsidian, or Roam Research, turning your reading into a personal knowledge base you actually revisit.

The research is more nuanced than "highlighting helps." Reviews of study techniques rate ordinary highlighting as low-utility, mostly because people highlight far too much (Dunlosky et al., 2013), and marking a page can even inflate your confidence without improving recall (Yue et al., 2015). What actually helps is selective highlighting paired with notes and review (Fowler & Barker, 1974). So the tool you pick matters less than how you use it. For the full research, see The Science of Highlighting.

If you're new to web highlighting, our guide on how to highlight text on web pages covers the basics and best practices.

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The Five Best Online Highlighters at a Glance

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Glasp: The Social Web Highlighter

Glasp is a social web highlighter built around the idea that learning is better when shared. Your highlights are public by default, creating a community where readers discover articles through each other's reading and learn from different perspectives on the same content.

What Makes Glasp Unique

Social learning by design. Glasp is the only highlighter where you can see what other people are highlighting across the entire web. You can follow readers whose interests overlap with yours, explore topics through community highlights, and find articles you would never have surfaced on your own. Research on social annotation shows that reading alongside others improves comprehension and retention, and Glasp is built on that principle.

Comprehensive export options. Glasp lets you export highlights in .txt, .md, .html, .csv, and image formats. It integrates directly with Readwise, and exports to Notion, Obsidian, and Roam Research through file export. You can export by article or in bulk, so your data is always portable.

YouTube transcript highlighting. Glasp displays YouTube video transcripts in a sidebar, letting you highlight and annotate them just like a web article. Timestamps are linked, so you can jump to the exact moment in the video. See YouTube Summary for the full workflow.

Kindle import. If you highlight books on Kindle, Glasp can import those Kindle highlights into your profile, bringing your physical and digital reading into one place.

Profile page as a knowledge portfolio. Your Glasp profile shows all your highlights, notes, and reading history in one place. It includes a daily activity tracker and an Atomic Graph that visualizes connections between your tags and topics.

Example: Kazuki's profile page on Glasp

Atomic Graph: visualize connections between your reading topics

Glasp Highlights & Notes

• Four highlight colors for categorization
• Inline notes on any highlight
• Tag system for organizing articles across topics
• "Pile-on" notifications when followers highlight the same article
• Community reactions and following

Pricing

Glasp's core is free. Highlighting, four colors, notes, tags, full export, Kindle import, YouTube transcript highlighting, and the social community cost nothing and always have. Glasp also offers optional paid plans, Pro at $15/month and Unlimited at $36/month (cheaper billed yearly), that raise AI usage limits such as AI chat credits, PDF summaries, and YouTube channel tracking. If you never touch the heavier AI features, the free plan covers everything a highlighter needs.

Best For

Readers who want to build a public knowledge portfolio, learn from others, and export their highlights into their existing workflow. Students, writers, researchers, and lifelong learners who value the social dimension of reading.

https://www.youtube.com/watch?v=Tgbszoeokv4

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Hypothesis: The Academic Annotation Standard

Hypothesis is an open-source annotation tool widely used in universities, research groups, and journalism. It focuses on collaborative, layered annotation rather than personal highlighting. If you have ever wanted to annotate a web page and discuss it with a reading group, Hypothesis is built for exactly that.

What Makes Hypothesis Unique

Three visibility layers. Every annotation can be public (visible to anyone with Hypothesis), group-only (shared with a specific group), or private (only you). That makes it flexible for everything from open discussion to confidential research.

Non-profit and open-source. Hypothesis is built by a non-profit organization, which means no ads, no data monetization, and long-term trust that the tool will not disappear behind a paywall. The code is open-source and, as of 2026, still actively maintained.

Deep academic integration. Many learning management systems (Canvas, Moodle, Blackboard) integrate Hypothesis directly. Professors can create reading assignments where students annotate the same text and discuss in the margins.

Standards-based annotation. Hypothesis uses the W3C Web Annotation standard, so your annotations are interoperable and not locked into a proprietary format. It now works across web pages, PDFs, and EPUB files.

Hypothesis Highlights & Notes

• Unlimited highlight colors (configurable)
• Rich-text annotations with Markdown support
• Threaded replies on annotations
• Group creation and management
• Public annotation layer across the web

Pricing

Hypothesis is free for individuals and groups. They offer paid plans for enterprise LMS integration.

Best For

Academics, research teams, reading groups, and journalists who need collaborative annotation with granular privacy controls. Particularly strong for university courses and peer review.

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Liner: AI Search With a Highlighter Attached

Liner began as a simple web highlighter. By 2026 it has repositioned as an AI search engine that pitches itself against Perplexity and ChatGPT, delivering answers with cited sources. The highlighter that made its name is still there, but it's now one feature inside a research assistant rather than the main event.

What Makes Liner Unique

AI search with citations. Liner's core product is now an AI copilot for Google and the open web. Ask a question and it returns a synthesized answer with references and follow-up suggestions. It also offers a Deep Research mode on paid plans. If you want search and highlighting under one roof, that combination is Liner's pitch.

Mobile apps. Liner is one of the few tools in this list with full-featured mobile apps for both iOS and Android. You can highlight or search on your phone, tablet, or desktop and everything syncs.

Highlighting and discovery. The classic highlighter still lets you mark web pages and PDFs, add comments, and organize saved passages. Public highlights appear in the Liner community, where users can react and reply.

YouTube and PDF summaries. Like Glasp, Liner can summarize YouTube videos and PDFs and save timestamped notes, so you can return to the exact point where you left off.

Liner Highlights & Notes

• Web and PDF highlighting with comments and replies
• Folder-based organization
• AI search with cited answers and follow-ups
• YouTube and PDF summaries
• iOS and Android apps

Pricing

Liner keeps a free tier with unlimited web highlighting and a daily cap on AI copilot chats. Paid plans start around $15/month (billed annually) and unlock Deep Research, higher usage limits, and unlimited file uploads. Because the paid value is now mostly about AI search rather than highlighting, Liner has become an expensive choice if all you want is to mark up articles.

Best For

Users who want AI-powered search and research summaries alongside a highlighter, and who need mobile apps. If you only want to highlight, a free tool will serve you better.

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Weava: Highlighting for Research Teams

Weava is designed for collaborative research. Its folder-based system lets teams organize and share highlights by project, making it a strong choice for group work and academic research teams.

What Makes Weava Unique

Folder-based collaboration. Weava organizes highlights into folders. Team members can be invited to shared folders where they can access, edit, and comment on each other's highlights. That suits research projects where several people read and annotate the same body of literature.

Image saving. With a premium plan, Weava lets you save images alongside your text highlights, which helps for research that involves visual data, charts, or diagrams.

Clean research interface. Weava's profile page organizes highlights by article in a list view, making it easy to search and browse even when you have hundreds of highlighted pages.

Weava Highlights & Notes

• Customizable highlight colors (up to 10 per folder on premium)
• Sub-folders for organizing large projects
• In-group comments and discussion
• Export to Word, Excel, Text, and CSV
• PDF annotation support

Pricing

Weava is free to use with unlimited highlights and notes. Premium is $7.99/month, frequently discounted to $3.99/month, and cheaper billed yearly. Students and educators can get a large discount. Premium unlocks unlimited folders, custom colors, image saving, and group collaboration.

Best For

Research teams, study groups, and organizations that need shared folders with controlled access. Students working on group projects or thesis research.

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Web Highlights: Minimalist and Privacy-Focused

Web Highlights takes a minimalist approach to web highlighting. It focuses on doing one thing well: letting you highlight and tag web pages and PDFs with a clean, fast interface. If you want a simple tool without a social feed, Web Highlights is a strong option.

What Makes Web Highlights Unique

Tag-based organization. Web Highlights uses a flat tag system rather than folders or social feeds. You tag your highlights, then search or filter by tag later. It's simple but effective for personal knowledge management.

Firefox support. Unlike most highlighters, Web Highlights supports Firefox in addition to Chrome, Edge, Brave, and Opera, which makes it accessible to a broader set of users.

Privacy-first design. Your highlights are private by default. There's no public feed and no public profiles. If you want a highlighting tool that stays out of your way, this is it.

AI summaries and notes. Recent versions added AI summaries of pages and PDFs plus richer note-taking, so you can capture the gist of a long article without reading every line.

Web Highlights Features

• Multiple highlight colors
• Tag-based organization
• Markdown export (Notion-friendly)
• AI page and PDF summaries
• Cross-browser support including Firefox

Pricing

The core is free: unlimited highlights, bookmarks, notes, and tags, plus export. Premium and Ultimate plans, starting around $5/month with a short free trial, sync your highlights to the cloud and unlock the web app and AI features.

Best For

Users who want a clean, private highlighting tool without a social feed. Firefox users who cannot use Chrome-only extensions. Minimalists who prefer tags over folders or feeds.

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Feature Comparison Table

Here is a side-by-side comparison of all five highlighters across the features that matter most.

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Which Highlighter Is Right for You?

The best highlighter depends on how you read and what you want to do with your highlights.

For social learning and knowledge sharing: Glasp

If you believe learning is better when shared, Glasp is the clear choice. It's the only tool where your reading becomes a public knowledge portfolio that others can learn from. Free core pricing, comprehensive export, and a growing community of readers make it the best all-around web highlighter for most people.

👉 Get started with Glasp for free

For academic annotation and research groups: Hypothesis

If you're in a university setting, working on collaborative research, or need fine-grained privacy controls (public, group, private), Hypothesis is the standard. Its open-source, non-profit model and LMS integrations make it the trusted choice for academic environments.

For AI-powered search and mobile use: Liner

If you want a tool that answers research questions with cited sources and works well on mobile, Liner is the strongest option, and the highlighter comes along for the ride. Just know you're paying for AI search, not for highlighting.

For team research with shared folders: Weava

If you're working on a group research project and need shared folders with access controls, Weava's collaboration model is purpose-built for this. It's the best choice for structured team research.

For minimalist, private highlighting: Web Highlights

If you want a clean, fast, private tool with Firefox support and no social feed, Web Highlights does exactly what it says. No distractions, just your highlights.

For a PDF-first workflow specifically, see our dedicated comparison of the best PDF highlighters.

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How to Get the Most Out of Any Highlighter

No matter which tool you choose, how you highlight matters more than the tool itself. Research shows that passive, indiscriminate highlighting provides little benefit (Dunlosky et al., 2013). Selective highlighting combined with notes and review does far better (Fowler & Barker, 1974).

Here are the key practices that make highlighting effective:

Be selective. Highlight no more than 10-20% of any text. One sentence per paragraph is a good rule of thumb. If you highlight everything, you highlight nothing.

Add notes. A highlight without a note loses context over time. Write a brief annotation for every few highlights. Tools like Glasp and Hypothesis make this easy with inline note fields.

Use a color system. If your tool supports multiple colors, assign meaning to each one. For example: yellow for key ideas, green for evidence, blue for questions, pink for connections to other readings.

Review regularly. Highlights you never revisit are wasted effort. Schedule a weekly review, or use a tool like Glasp that resurfaces your recent reading for you.

Export and connect. The best highlighters let you move your data into your broader knowledge system. Export into Notion, Obsidian, or Roam Research to connect highlights across sources and build a personal knowledge base. If you're comparing destinations, our roundup of the best note-taking apps covers where your highlights should land.

For a complete guide to highlighting best practices backed by research, see How to Highlight Text on Web Pages. For the science behind why highlighting works (and when it doesn't), see The Science of Highlighting.

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Frequently Asked Questions

What is the best free online highlighter?

Glasp is the best free online highlighter. Its highlighting, four colors, notes, tags, full export (.txt, .md, .html, .csv), Readwise integration, Kindle import, YouTube transcript highlighting, and social community are all free. Glasp does offer optional paid plans (from $15/month) for heavier AI usage, but you never need them to highlight. Hypothesis is also free and open-source, making it a strong choice for academic use.

Can I use an online highlighter on any website?

Most browser extension highlighters work on nearly any website. Exceptions include pages that block extensions (like the Chrome Web Store), some single-page apps with unusual rendering, and pages behind strict Content Security Policies. For the vast majority of articles, blogs, and web pages, highlighting works seamlessly.

Can I export my highlights to Notion, Obsidian, or Readwise?

Glasp supports direct export to Readwise and file-based export (.md, .txt, .csv, .html) that works with Notion, Obsidian, and Roam Research. Web Highlights offers Markdown export too. Most other highlighters have limited export options, so check the export features before committing if portability matters to you.

Are my highlights private?

It depends on the tool. Glasp highlights are public by default (social learning model). Hypothesis lets you choose public, group, or private for each annotation. Liner lets you toggle between public and private. Weava is private by default with optional group sharing. Web Highlights is fully private. Choose the tool that matches your comfort level with visibility.

Do any online highlighters work on mobile?

Glasp has iOS and Android apps with an in-app Reader for highlighting, plus an iOS Safari extension for marking up web pages on your phone. Liner also has full mobile apps for both iOS and Android. Weava has an iOS app. Hypothesis and Web Highlights are primarily desktop browser tools. If mobile highlighting is critical to your workflow, Glasp and Liner are the strongest options.

Which highlighter is best for students?

For individual study, Glasp offers the best combination of free features, export options, and social learning. For group annotation assignments, Hypothesis is widely used in university courses and integrates with learning management systems like Canvas and Moodle. For collaborative research projects, Weava's shared folders work well for group work.

Is Glasp better than Liner?

Glasp and Liner now serve different goals. Glasp is a free-core social highlighter focused on learning and knowledge sharing, with comprehensive export. Liner has become an AI search engine with a highlighter attached, and its paid plans are priced for AI research rather than highlighting. If you value community, export flexibility, and a free highlighter, choose Glasp. If you mainly want AI search with cited answers, consider Liner.

Does highlighting actually improve learning?

Only when it's done well. Reviews rate ordinary highlighting as low-utility because most people highlight too much (Dunlosky et al., 2013), and marking a page can inflate your sense of mastery without improving recall (Yue et al., 2015). It pays off when you highlight selectively (10-20% of text), add notes, and review, which turns passive marking into active evaluation (Fowler & Barker, 1974). For the full research, see The Science of Highlighting.

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