5 Best Tools to Annotate and Highlight Web Pages for Research and Study

When you share a link with someone, the relevant part is just a small snippet or two. Use these free tools to annotate or highlight the important part to draw attention to it.

All article apps have a highlight marker (often with different colors) and a way to write sticky notes or comments anywhere on the page. Both features are great when you want to add notes for research and study, whether for your personal needs or for your friends. Beyond that, there are a few small features that enhance each tool for different needs.

1. Diigo (Chrome, Bookmarklet, Android, iOS): Annotations, Highlights, Comments on Any Web Page

Diigo is a simple highlighter tool for web pages that also lets you add comments and share with friends

Diigo is one of the oldest and most popular online annotation tools. Sure, it’s changed a lot over the years, but it’s a simple and reliable app for adding highlights and comments to any webpage.

Available as a Chrome extension or bookmarklet for other browsers, Diigo is intuitive to use. Select any text on any post and you can highlight it in one of four colors. You can also add a small note to the highlight or a floating note anywhere on the page. You can also share notes with collaborators and you can also change their colors. As Diigo says in its help section, you might want to mentally assign a specific purpose to each color, thus keeping your highlights organized for your eyes.


All annotations on a page can be seen quickly through the extension shortcut. You can also view and organize annotations in Diigo’s web dashboard. You can create groups in Diigo and share annotations and highlights with them and as PDFs.

Diigo is also a bookmark app, saving every page and its annotations to your account and syncing it across all devices. On phones, Diigo is available as a standalone browser with many of the same features.

To download: Diigo for Chrome | Bookmarklet (Free)

To download: Diigo Browser for Android | iOS (Free)

2. Smort (Web): Annotate and edit articles to share with your friends

Smort is an installation-free annotation tool for highlighting text or completely editing and modifying text in online articles before sharing with friends.

Most annotation apps only allow you to add highlights, sticky notes, and comments to the article. Smort lets you edit the content of the article itself, remove entire paragraphs or images, add text, and more. And you don’t need to install anything to do that either.

When you want to share an article, add “smort.io” before the URL and hit enter to open it in the Smort editor. Here you can edit the article as you see fit, with a simple Markdown editor to edit text and text formatting. Smort also supports reflections of four different colors, so you can add a note at the top of the article about what each color means. There are handy undo and redo buttons at the top if you make any mistakes.

Smort automatically generates a table of contents for each article for easy navigation. As an editor, you can also switch between four different font types and a dark or light mode for easier reading. Once you’re done editing, click the Share button to generate a unique link that lasts for seven days from when it was created. After that, if you make any other changes, you will need to regenerate a new link and share it.

3. Spade (Chrome): Privately Annotate and Highlight Web Pages

Spade is a fast and elegant app for privately writing annotations and notes on any webpage

Spade is a great free tool to make your search for essays and articles easier while keeping it private. It is a Chrome browser extension with annotation and highlighting capabilities and some other neat tricks like quotes and machine learning analysis.

Once the extension is installed, Spade appears as a small button in one of the four corners of every web page (customizable by you). Click the button to expand a toolbar with an annotation pen to draw or doodle anywhere and a highlight marker. You can control the dot size for each and choose from seven different colors. Spade also lets you create a text box anywhere on the page for writing notes and has a simple eraser to take it all away. All of these highlights are shared and synced with your Spade web account so you can access them anywhere.

In our tests, sharing a page made in Spade did not show the annotations or highlights to the recipient. However, you can export any annotated page as a PDF file with all notes intact.

In addition to these annotation features, Spade includes a built-in citation tool for research articles that automatically cites pages from major journals. It also uses machine learning to assess the credibility of a web page and summarizes large text accurately.

To download: Spade for Chrome (Free)

4. Hypothes.is (Web, Chrome): Collaborative Annotations and Web Highlights

Hypothes.is is the best free app to annotate and highlight web pages in collaboration with friends, and even write comments and notes

If you’re working with a study group or team on a research project that needs to share links with annotations, Hypothesis is as good as it gets. This Chrome extension is much lighter than the others and focuses on the ability to collaborate. Moreover, it is ad-free and has no hidden costs or restrictions.

All users will need to create a Hypothesis account before installing the extension. Then, create a private group if you want your shares to remain private with your friends, or use the default Public tab to let anyone see the annotations.

On any web page, you can select text to turn it into a highlight or an annotation (that is, highlight with a note). Each of these items appears in your hypothesis sidebar in chronological order on this page. Collaborators can add comments and respond to each annotation individually. You can also add a note on any page that appears in the Notes section.

The Hypothesis Web Dashboard makes it easy to search through all your highlights and notes. In addition to a full-text search, you can add advanced operators (like username, group name, URL, or tag) to quickly find what you’re looking for.

To download: Hypothesis for Chrome (Free)

Liner is one of the best online annotation apps and has been for years, especially with its recent updates. Its wide support for different platforms makes it the go-to choice if you switch between phones, tablets, and computers, but need one place to collect all your highlights.

Once you have created an account and logged in, you can select any text to highlight it. You can also add a comment to any highlight and share it with your friends and collaborators. The free basic account only lets you work with one highlighter color and limits you to 15 highlights per page. For more colors and unlimited highlights, you need the Premium plan.

Liner also works with YouTube, which makes it stand out. You can highlight any part of a YouTube video, much like highlighting text on a web page. It worked fine for us on browsers but not on mobile.

The app has a few other features worth checking out, like how it displays highlights most popular by other users on any page. And the dashboard can distinguish between text and video highlights.

To download: Liner for Android | iOS (Free)

To download: Liner for Chrome | Edge | safari | Whale (Free)

Use colors as your own organizing system

No matter which annotation tool you use, there is a nifty hack suggested by several app users and blogs. Since most of them allow you to use different colors for highlighting or annotation, use those colors for your own marking or organization system.

For example, when you highlight text in yellow, it means “worth reading”, but when you highlight it in red, it means “use as is in the research paper”. Do this for all colors. Nobody but you needs to know what each color means, but as long as you’re consistent with how you use them, it’ll give you a useful system.


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About the Author

Calvin W. Soper