An online bookmark manager which also can act as a content archiver. Can save content as HTML, PDF, or PNG in addition to storing links for later reference. Automatic summarization and tagging of links. Multiple user accounts. Multiple back-end databases (SQLite default). Annotation support. Written in Python 3. Don't know if there's an API.
A personal knowledge repository for PDF and web content supporting offline-first caching, annotations of HTML as well as PDFs, and flashcards. If it's a document of some kind, it can manage it, including allowing annotations. Keeps track of where you left off in a particular document. Everything is stored locally; Git can be used to sync repos. Tries to be cross-platform.
Client side uses Electron, server side uses node.js.