Highlight text or click any element, with private and public notes and community rankings.

Best for: Readers who want visible on-page annotations plus a browsable public layer.

Social highlighting with a follow feed and PDF support.

Best for: Readers who treat highlighting as a social activity.

Highlighting organized into research folders, private by default.

Best for: Students and researchers running a structured literature review.

Open-source annotation with groups and an API.

Best for: Classrooms, teams and anyone who needs to build on an annotation API.

Social reading and highlighting with friends.

Best for: Reading clubs and groups that want a shared, social reading space.

Read-it-later app that imports highlights from many sources.

Best for: People who want one inbox for articles, feeds and imported highlights.

Bookmark manager that keeps highlights and notes alongside links.

Best for: Collectors who organize bookmarks and want highlights attached to them.