Why You Need an Online Highlighter
If you read articles, research papers, or blog posts on the web, you have probably experienced this: you find an incredible insight, close the tab, and never find it again. Bookmarking saves the page, but not the specific passage that mattered to you. Copy-pasting into a doc works, but it loses the original context and creates a mess of disconnected snippets.
Online highlighters solve this by letting you mark text directly on any web page, attach your own notes, and organize everything in one place. The best tools also let you export your highlights into note-taking apps like Notion, Obsidian, or Roam Research, turning your reading into a searchable personal knowledge base.
Research backs this up. Studies show that selective highlighting, combined with annotation and regular review, significantly improves comprehension and retention (Yue et al., 2015). The key is choosing a tool that fits your workflow and makes it easy to highlight well. For a deep dive into the research, see The Science of Highlighting.
If you are new to web highlighting, our guide on how to highlight text on web pages covers the basics and best practices.
The Five Best Online Highlighters at a Glance
| Tool | Best For | Price | Browsers | Key Strength |
|---|---|---|---|---|
| Glasp | Social learning, knowledge sharing | Free | Chrome, Safari, Brave, Edge, Opera | Social community + full export |
| Hypothesis | Academic annotation, research | Free | Chrome, Firefox, Edge, Safari (via bookmarklet) | Open-source, group layers |
| Liner | AI-powered discovery | Freemium ($9.99-17.99/mo) | Chrome, Safari, Edge, iOS, Android | AI recommendations |
| Weava | Team and group research | Freemium ($3.99/mo) | Chrome, Safari, Edge, iOS | Collaborative folders |
| Web Highlights | Minimalist highlighting | Freemium | Chrome, Edge, Brave, Opera, Firefox | Clean, tag-based organization |
Glasp: The Social Web Highlighter
Glasp is a free social web highlighter built around the idea that learning is better when shared. Your highlights are public by default, creating a community where readers can 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 discover articles you would never have found on your own. Research from Cornell University shows that social annotation improves comprehension and retention, and Glasp is built on this principle.
Comprehensive export options. Glasp lets you export highlights in .txt, .md, .html, .csv, and image formats. It integrates directly with Readwise, Notion, Obsidian, and Roam Research. You can export by article or in bulk. 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.
Kindle import. If you highlight books on Kindle, Glasp can import those 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 is completely free. There are no premium plans or paid features.
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
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). This 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 there are no ads, no data monetization, and long-term trust that the tool will not disappear behind a paywall. The code is open-source.
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, meaning your annotations are interoperable and not locked into a proprietary format.
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.
Liner: AI-Powered Highlighting and Discovery
Liner started as a simple highlighter but has evolved into an AI-powered content discovery platform. It combines highlighting with personalized article recommendations, making it a tool for both capturing and finding information.
What Makes Liner Unique
AI-powered recommendations. Liner uses your highlighting history to recommend articles and content you might find interesting. The "Pages read together" feature shows related content based on what other Liner users have read alongside the same article.
Mobile apps. Liner is one of the few highlighters with full-featured mobile apps for both iOS and Android. You can highlight on your phone, tablet, or desktop and everything syncs.
Social features with privacy control. You can choose to make each highlight public or private. Public highlights appear in the Liner community, where other users can react with thumbs-up, comment, and reply.
YouTube timestamp notes. Like Glasp, Liner supports saving timestamps while watching YouTube videos. You can come back to the exact point in the video where you left a note.
Liner Highlights & Notes
- Multiple highlight colors (more with premium)
- Inline comments and replies
- Folder-based organization
- Mentions to invite others into conversations
- Calendar view for tracking reading streaks
Pricing
Free plan with basic features. Premium: $9.99/month. Pro: $17.99/month. Premium unlocks all highlight colors, themes, and ad-free experience.
Best For
Users who want AI-driven content discovery alongside their highlighting workflow. Mobile-first users who need to highlight on both phone and desktop.
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 the best 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. This makes it well-suited for research projects where multiple people are reading and annotating the same body of literature.
Image saving. With a premium plan, Weava lets you save images alongside your text highlights, which is useful 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
Free plan with basic features. Premium: $3.99/month. 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.
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 with a clean, fast interface. If you want a simple tool without social features or AI, 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, and later you search or filter by tag. It is simple but effective for personal knowledge management.
Firefox support. Unlike most highlighters, Web Highlights supports Firefox in addition to Chrome, Edge, Brave, and Opera. This makes it accessible to a broader set of users.
Privacy-first design. Your highlights are private by default. There is no social layer, no community feed, no public profiles. If you want a highlighting tool that stays out of your way, this is it.
Offline access. Web Highlights can store highlights locally, giving you access even without an internet connection.
Web Highlights Features
- Multiple highlight colors
- Tag-based organization
- Markdown export
- Bookmark management
- Cross-browser support including Firefox
Pricing
Free plan with limited highlights. Premium plans available for unlimited usage.
Best For
Users who want a clean, private highlighting tool without social features. Firefox users who cannot use Chrome-only extensions. Minimalists who prefer tags over folders or feeds.
Feature Comparison Table
Here is a side-by-side comparison of all five highlighters across the features that matter most.
| Feature | Glasp | Hypothesis | Liner | Weava | Web Highlights |
|---|---|---|---|---|---|
| Price | Free | Free | Freemium ($9.99+/mo) | Freemium ($3.99/mo) | Freemium |
| Web highlighting | Yes | Yes | Yes | Yes | Yes |
| PDF highlighting | Yes | Yes | Yes | Yes | Yes |
| YouTube highlighting | Yes | No | Yes (timestamps) | No | No |
| Highlight colors | 4 | Configurable | Limited (more on premium) | Customizable (premium) | Multiple |
| Notes/Annotations | Yes | Yes (rich-text, threaded) | Yes (comments, replies) | Yes (in-group) | Yes |
| Export formats | .txt, .md, .html, .csv, image | Limited | Word, Text | Word, Excel, Text, CSV | Markdown |
| Readwise integration | Yes | No | No | No | No |
| Notion/Obsidian export | Yes (via Readwise + direct) | No | No | No | No |
| Kindle import | Yes | No | No | No | No |
| Mobile app | No | No (bookmarklet) | Yes (iOS, Android) | Yes (iOS only) | No |
| Firefox support | No | Yes | No | No | Yes |
| Visibility | Public | Public/Group/Private | Public or Private | Private (Group on premium) | Private |
| Social features | Follow, reactions, community feed | Public annotation layer | Likes, comments, mentions | Group comments | None |
| Group/Team function | No | Yes (free) | No | Yes (premium) | No |
| AI features | AI summary | No | AI recommendations | No | No |
| Open-source | No | Yes | No | No | No |
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 that learning is better when shared, Glasp is the clear choice. It is the only tool where your reading becomes a public knowledge portfolio that others can learn from. The combination of free pricing, comprehensive export options, and a growing community of readers makes it the best all-around web highlighter for most users.
👉 Get started with Glasp for free
For academic annotation and research groups: Hypothesis
If you are 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 discovery and mobile use: Liner
If you want your highlighter to actively help you find new content based on your reading habits, and you need a mobile app that works well, Liner is the strongest option. The AI recommendation engine sets it apart from simpler tools.
For team research with shared folders: Weava
If you are working on a group research project and need shared folders with access controls, Weava's collaboration model is purpose-built for this. It is the best choice for structured team research.
For minimalist, private highlighting: Web Highlights
If you want a clean, fast, private tool with no social features and Firefox support, Web Highlights does exactly what it says. No distractions, no community, just your highlights.
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, but selective highlighting combined with notes and review is a powerful learning strategy (Dunlosky et al., 2013; 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 are highlighting everything, you are highlighting 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 sends weekly recap emails to surface your recent reading.
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.
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.
Frequently Asked Questions
What is the best free online highlighter?
Glasp is the best free online highlighter. It offers four highlight colors, notes, tags, full export options (.txt, .md, .html, .csv), Readwise integration, Kindle import, YouTube transcript highlighting, and a social community, all completely free with no premium paywall. 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 applications 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. Most other highlighters have limited export options. If portability of your data is important, check the export features before committing to a tool.
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?
Liner has full-featured mobile apps for both iOS and Android. Weava has an iOS app. Most other highlighters (Glasp, Hypothesis, Web Highlights) are desktop-only browser extensions. If mobile highlighting is critical to your workflow, Liner is currently the strongest option.
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 serve different needs. Glasp is fully free, focused on social learning and knowledge sharing, with comprehensive export options. Liner is freemium, focused on AI-powered content discovery, and has mobile apps. If you value community, export flexibility, and zero cost, choose Glasp. If you want AI recommendations and mobile access, consider Liner.
Does highlighting actually improve learning?
Yes, when done correctly. Research by Yue et al. (2015) shows that selective highlighting improves recall by forcing active evaluation of what matters. The key is to highlight selectively (10-20% of text), add notes, and review regularly. Passive highlighting of everything is ineffective. For the full research, see The Science of Highlighting.