Margin
Web annotation platform built on the AT Protocol that lets users highlight, annotate, and bookmark any webpage with data stored on their own AT Protocol identity
Margin is an alternative to
Hypothesis
Hypothesis is an open-source web annotation platform for highlighting, annotating, and discussing web pages and documents.
Genius
Genius is a web annotation platform for adding notes, commentary, and explanations to song lyrics, news, and other web content.
Diigo
Diigo is a web annotation and bookmarking platform for highlighting, annotating, and organizing web pages.