Compare Glasp, PDF & Web Highlighter, Voila, and Sider: Which Extension is the Best?
AI-powered web highlighter for websites, PDFs, and YouTube videos. Build your AI clone from highlights and connect with 1M+ learners worldwide. | Web Highlights lets you highlight text on any website or PDF, create notes, and generate AI summaries. It’s free, simple, and doesn’t require signing up. The best online PDF and web highlighter. | |||
| Key Features A summary of the most important features offered by each extension. |
|
| • Universal Website Integration: Works on any website with context awareness • Gmail Integration: Seamless email drafting and AI-powered instant replies • Expert Prompt Library: Pre-built prompts for various content types • Web Research: Real-time information gathering with reliable sources • Multi-language Support: Works in over 50 languages • Cross-platform Availability: Browser extension, desktop, and mobile apps • Privacy-First Design: GDPR compliant with no data storage on servers |
|
| Our Rating Tooltivity's expert review score for each extension, based on hands-on testing and research. | 8.9 | 9.8 Winner in this category | 9.1 | 8.7 |
| Total users Total active users across all major browsers: Chrome, Edge, Firefox, and Safari. | 506,682 | 112,696 | 90,548 | 8,035,097 Winner in this category |
| Total ratings Total number of user ratings received across all supported browsers. | 840 | 3,924 | 236 | 112,430 Winner in this category |
| Average rating Average user rating across all browsers, calculated from available store ratings. | 4.2 ⭐ | 4.8 ⭐ | 4.3 ⭐ | 4.9 ⭐ Winner in this category |
| Entry Level Price The minimum price required to start using the extension. "Free" means a free tier is available. | Free | Free | Free | Free |
| Chrome User rating and stats for the extension on Chrome browser. |  4.5 3.78 Average Chrome Web Store rating from the last 100 reviews 500.0K+Users | 4.8 4.87 Average Chrome Web Store rating from the last 100 reviews 100.0K+Users | 4.7 4.77 Average Chrome Web Store rating from the last 100 reviews 80.0K+Users | 4.9 4.92 Average Chrome Web Store rating from the last 100 reviews 5.0M+Users Winner in this category |
| Edge User rating and stats for the extension on Edge browser. |  4.0 4.25 Average Microsoft Edge Store rating from the last 100 reviews 6.7K+Users | 4.7 4.70 Average Microsoft Edge Store rating from the last 100 reviews 11.8K+Users | 4.1 4.11 Average Microsoft Edge Store rating from the last 100 reviews 7.0K+Users | 4.8 4.32 Average Microsoft Edge Store rating from the last 100 reviews 3.0M+Users Winner in this category |
| Firefox User rating and stats for the extension on Firefox browser. | - |  5.0 5.00 Average Mozilla Firefox Add-ons Store rating from the last 100 reviews 888Users Winner in this category | 4.1 3.93 Average Mozilla Firefox Add-ons Store rating from the last 100 reviews 3.6K+Users | - |
| Safari User rating and stats for the extension on Safari browser. | - | - | - | - |
| Features Tooltivity's expert score for the 'Features' aspect of each extension. | 9.5 Highlighting features: In our tests, Glasp's highlighting features worked flawlessly. We were able to highlight text on a variety of websites, in PDF files, and even in YouTube transcripts without any issues. Thanks to the numerous color options and the ability to add notes to each highlight, we were able to easily organize and retrieve our information across different types of content. AI integration: We tried the AI summary feature with ChatGPT, Claude, and Gemini and found the results really useful for summarizing our highlights and asking questions. Social learning: We explored the social features by browsing other users' highlights and sharing our own. However, we found it a bit intrusive that this is mandatory in the free version. Export options: Exporting our highlights to Obsidian and Notion worked smoothly. We tested all available formats (Markdown, HTML, CSV, JSON) and found the flexibility helpful for integrating Glasp into our existing workflows. | 9.8 Web Highlights offers a range of features. In addition to its main function of highlighting text on websites and PDFs, it provides much more, making it the ideal tool for learning and self-improvement. Top Features of Web Highlights1. Highlighting websites & PDFs:  Web Highlights excels at one thing better than any other tool we tested—highlighting websites and PDFs. You don't even need an account. Just visit any site, highlight the text, and a marker icon will appear, letting you choose from different highlight colors. Once highlighted, your highlights are visible on the website. And the best thing: Your highlights will also be visible on the website if you reload the page. You not necessarily need the highlighter popup to mark up some text. In general, there are three ways to create a highlight:
In our tests, we could easily highlight several websites, and those highlights were effortlessly restored when revisiting them. It works seamlessly with both online and local PDFs.  All of your highlights are not only visible on the page but also accessible through the sidebar, which gives you a good overview of your highlights made. This is much like the highlighter sidebar which is common in PDF tools like Acrobat. Here is how it looks:  The sidebar gives you an outline of your highlights on the current page. 2. AI-powered summaries ✨ One of the things I like most is how smoothly the AI-powered summary feature gives you a quick overview of a website’s content. The AI summary feature in Web Highlights works entirely offline with Chrome’s built-in LLM, making it both super fast and completely private. You can choose from different summary styles depending on what you need:
 3. Create Notes & Tags:  You can either create tags & notes by using the sidebar or by clicking on a highlight on the page. This will open up a popup allowing you to add tags and notes to a specific highlight. Any changes you make on the pages are also directly visible in the sidebar. Making it a perfect research tool to work with large articles. Inside the sidebar you can then find all your highlights and bookmarks listed for the given tag. 4. Web App:  The best thing about Web Highlights is, that it can synchronize all your research to the corresponding web app at app.web-highlights.com. The web app can be opened in your browser but works perfetly on your phone. If you have opened the website before, you can even access your research when you are offline. The dashboard of the app shows all of your research in one place in a beautiful overview. You can also filter for specific tags or websites. 5. Save Bookmarks:  Web Highlights isn't just for highlighting text—it’s also great for saving pages as bookmarks. This way, you can either come back later to continue highlighting or easily find the page again. 6. Email reminders  A standout feature of Web Highlights is its email reminder, which works a lot like "snoozing" emails. You can set a reminder for a specific date and time by clicking the clock icon on a highlighted page. Web Highlights will then email you the article so you don’t forget to revisit it. This feature is unique among competitors, and we use it daily to get reminders for websites we need to return to later. 7. Export to Notion, Markdown, and more  Web Highlights gives you plenty of export options. With the Markdown export, you can easily send your research to any Second Brain or PKM tool you prefer. On top of that, it directly integrates with Notion and Capacities through full API connections. For instance, if you're on a highlighted page, just click the three dots in the sidebar and choose "Export to Notion." In seconds, a Notion page will be created. The same process works for Capacities. Winner in this category | 9.0 Voilà's features are impressively comprehensive and cover many areas, from simple AI chat to advanced content creation tools.  The integration with Gmail works flawlessly and makes email management much more efficient. The ability to respond to emails in a context-sensitive manner sets the tool apart from many of its competitors.  On websites, it is first necessary to highlight the desired text. However, if you want a summary of the website, for example, this is not a problem because you can simply highlight the entire website. A context-based AI chat that has access to the context of the current website would improve this even further.  Overall, the extension offers very powerful features, some of which are not even found in competitors' products. | 9.5 Sider offers a comprehensive range of functions and is designed to provide a solution for every possible use of AI. From AI writing assistance to PDF analysis, for example, it covers all areas for every blogger. Creatives also get their money's worth here, whether creating images from text or editing photos, Sider offers these functions in just one tool and integrates the functions of other providers into your one tool.  The number of integrated AI models, such as GPT-4o, Claude, or Gemini, also stands out. This ensures that users have access to the latest technology.  In summary, Sider offers almost all of the current possibilities of AI in one tool. |
| Performance Tooltivity's expert score for the 'Performance' aspect of each extension. | 8.7 In our experience, marking and saving content was quick and almost instantaneous on websites and in PDF files. The extension did not noticeably slow down our browsers. Most features worked reliably, but we occasionally encountered problems with YouTube transcription and AI summaries, which were also mentioned by users in their reviews. | 10 The extension performs seamlessly, allowing you to highlight websites and PDFs without any lag or interruptions. The full-text search functionality is quick and accurate, enabling you to find your highlights effortlessly. Additionally, the ability to sync your highlights across devices ensures that you can access your research from anywhere, enhancing your productivity. The best part is that the web app works entirely offline. So, you can access your research from any device, even without an internet connection. Winner in this category | 8.7 In our test, Voilà consistently delivered good performance on various websites and in different use cases. The AI responses are usually fast and relevant. The extension has no noticeable impact on browser performance. Some users report occasional delays during peak times, but this is common with AI tools. The tool processes large documents and complex queries without any problems. | 9.2 Sider generally performs well in the test with fast response times and reliable functions. The integration of multiple AI models ensures that users receive accurate and relevant information. However, there can be occasional delays, especially when using advanced features or at peak times. Continuous updates and optimizations could further improve performance. |
| Design Tooltivity's expert score for the 'Design' aspect of each extension. | 9.3 During our tests, the user interface appeared clear and intuitive. The sidebar did not interfere with reading, but was accessible at all times to view highlights and notes. We liked the color-coded highlights, which made it easier to scan and visually organize information. | 9.9 The design is clean and intuitive, making it easy to get started right away. We loved the customizable highlight colors and the overall look and feel of the sidebar. What users love most is the intuitive sidebar and the well-organized web app. It’s super easy to navigate and quickly find what you need. The web app also looks great on mobile devices, making it simple to access the articles you've read on your phone. Winner in this category | 9.3 The user interface is clear and intuitive. The seamless integration with Gmail is particularly well done. | 8.5 The design of Sider is very user-friendly, and the interface is quite clear, so it's easy to find anything. The sidebar is great because you can access features without leaving the page. However, it might feel cluttered for some people as there are so many options. A sleeker design could improve the user experience. |
| Value for Money Tooltivity's expert score for the 'Value for Money' aspect of each extension. | 8.8 We made extensive use of the free plan and found that unlimited tagging and basic organization and access to the social network is more than sufficient for most users. For heavy users, especially researchers and content creators, the additional AI features and private tags are worth the price of the Pro plan. The price is similar to that of competitors. Compared to other tools we've tested, Glasp offers a more comprehensive set of features, making the price competitive in the knowledge management space. For those of us who rely on knowledge management in our work, the time savings and improved organization easily justified the Pro subscription. | 9.5 Web Highlights can be used for free without signing up, providing access to a wide range of offline features. To fully enjoy the benefits of Web Highlights, including accessing your highlights and bookmarks from anywhere with automatic cloud-sync, you can upgrade to the PREMIUM or ULTIMATE version of the extension. The pricing plans are affordable, making it a cost-effective solution for students, researchers, and avid online readers. No other tool gives you this much value for so little cost. Winner in this category | 8.9 The free plan offers a good introduction to Voilà's features, but is quite limited. The premium plan for $6 per month offers excellent value for money for anyone who finds that they use the tool regularly after using up their free requests. In our opinion, the advanced features, such as chatting with YouTube videos and generating images, justify the price. For frequent users who also want to use AI for their documents or chat with images, the Ultimate version is worthwhile. At $14, the price is still relatively inexpensive compared to competitors with similar features. | 7.8 While Sider offers a free version with limited requirements, the premium plans can be expensive for casual users. While the feature set justifies the cost for power users, those who only need basic features may find it expensive. The availability of different pricing tiers offers flexibility, but an intermediate solution with a cheaper option could appeal to a wider audience. |
| Ease of Use Tooltivity's expert score for the 'Ease of Use' aspect of each extension. | 9.0 Setting up Glasp was quick—we installed the extension, created an account, and were able to start tagging within minutes. The introductory video was clear and helped us get up to speed quickly. When we looked at features such as creating AI clones and advanced export options, it became a little more complex. It took some trial and error to figure out how to best use these tools. Overall, the tool is definitely designed so that anyone can use most of its features. | 9.5 We can’t think of a simpler Chrome Extension to start with than this one. The best part? It works seamlessly right out of the box, no account needed. Installing it is a breeze, and you can easily add the extension to both Google Chrome and Microsoft Edge. Once installed, a highlighter pop-up appears whenever you highlight text on any website. The process is intuitive and easy to grasp. If you need help, Web Highlights offers plenty of blog posts that guide you through its features. With so many powerful features, Web Highlights might seem a bit overwhelming at first, but everything falls into place quickly. The tagging system, in particular, is easy to use and much simpler than traditional folders. That’s why we rate it 9.5 out of 10. It’s extremely user-friendly, though some features might take a little time to fully appreciate. Winner in this category | 9.4 Voilà offers an excellent balance between performance and simplicity. The tutorial system is well-designed and suitable for beginners. The keyboard shortcuts make navigation intuitive once you have learned them. The context-sensitive functions work automatically, so manual configurations are rarely necessary. Creating custom prompts and actions takes some time to learn, but it is worth the effort. | 9.0 In our tests, Sider was easy to use without having to learn how to use it. The tooltips and instructions help you get started right away. It works well in our tests with popular browsers such as Chrome and Edge, which are quick to install and use. However, if you want to delve into the advanced functions, it can take a while to get to grips with everything. Basic users might be a little overwhelmed here. |
| Security & Privacy Tooltivity's expert score for the 'Security & Privacy' aspect of each extension. | 8.0 During our review, we found that Glasp collects website content and some personal data to enable its features. By default, some of our highlights were shared publicly. We had to adjust our settings to keep the information private. Therefore, it is important to be aware of this, especially since it is mandatory for free users. | 9.9 In the Security & Privacy category, we give Web Highlights a solid 10/10. The fact that you can use this tool offline without needing an account sets it apart from its competitors. Even if you opt for cloud sync by creating an account, Web Highlights puts data privacy first. Your highlights, notes, and tags are visible only to you by default unless you decide to share them. Your data isn’t sold to third parties, nor is it used or transferred for anything beyond the extension's core functionality. This dedication to data privacy ensures your information stays secure and confidential. Winner in this category | 9.0 Data protection is a high priority for Voilà. The extension complies with the GDPR and transparently lists its data processing methods. The tool does not store conversations on its servers, which is important for companies, among others. The privacy policy is comprehensive and explains data usage clearly and concisely. The option to use your own API keys offers additional control and flexibility for anyone who needs it. The only minor criticism is the use of third-party analytics tools, which is a common practice for such extensions. | 8.0 Sider stores the data on Amazon's US servers. The data protection guidelines are transparent and users have control over their data. However, usage data is collected for analysis purposes, which not every user will find acceptable. The assurance that data is never passed on and no spam messages are sent is a positive aspect. |
| Conclusion A summary of our findings and final thoughts for each extension. | Glasp Web Highlighter has proven in testing that it can help users interact with digital content in a useful way in their everyday lives. It is not just a highlighting tool, but a comprehensive organization system that combines the best aspects of social learning with AI technology. What we particularly appreciate about Glasp is that it encourages a more intensive engagement with the content. Instead of passively bookmarking pages, users are motivated to highlight specific passages and add notes, which leads to better retention and understanding. It is therefore particularly specialized in learning content. However, Glasp is not without its challenges. The limitations of the AI features and privacy restrictions in the free version may be problematic for many users. In addition, some users report technical issues with the YouTube transcription features. For researchers, students, and content creators who are seriously interested in building a kind of second brain, Glasp offers compelling value. The combination of highlighting, AI summarization, and social learning creates a unique ecosystem that is difficult to replicate with other tools. Casual users, however, may find the complexity and pricing structure daunting. | We have been using Web Highlights - PDF & Web Highlighter for years and can confidently say it’s a top-notch tool for anyone who spends a lot of time reading online. Its user-friendly design and powerful features make it a must-have for students, researchers, and professionals alike. The free version is fantastic, but if you need more advanced features, the premium options are well worth the price. If you’re serious about staying organized while reading online, we highly recommend giving Web Highlights a try. | Voilà impressed us with its seamless integration, especially with Gmail, and its powerful AI features. It is a tool that simply aims to integrate AI into everyday life for every user in order to simplify everyday tasks. The free plan allows you to test it out sufficiently, and if you're convinced, the Pro plan offers excellent value for anyone who values productivity. The tool's ability to respond to emails contextually and directly integrate highlighted text from any website sets it apart from the competition. The only thing that could improve it is the ability to directly integrate the current website without highlighting text. We recommend Voilà for professionals, content creators, and anyone who wants to optimize their AI-powered workflow without sacrificing privacy or functionality. | Sider is an AI tool that can significantly increase user productivity across multiple platforms. The high number of features, from writing assistance to image editing, makes it a versatile choice for truly anyone. Although it excels in many areas, there is still room for improvement. In particular, the sometimes high prices will put normal users off. Overall, Sider is a valuable tool for anyone who wants to combine almost all the possibilities of AI in one tool and is willing to pay for it. |
| Our Recommendation | In our comparison between Glasp, PDF & Web Highlighter, Voila, and Sider, PDF & Web Highlighter came out on top, scoring 9.8. Sider is the most widely used, with over 8 million users and 112k+ reviews, but PDF & Web Highlighter outperformed it in our review. User reviews for Glasp, PDF & Web Highlighter, and Voila reflect our findings, while we rate Sider lower than users do. Notably, Sider has the highest user rating in the Chrome Web Store at 4.86, which is even higher than our rating of 8.7. There are some noticeable differences between these extensions, so it's worth considering your priorities and the details below.
If you want a quick recommendation, PDF & Web Highlighter is our top pick. But as always, the best choice depends on what matters most to you. | |||
