Logseq
Logseq is an open-source, local-first outliner for personal knowledge management that stores notes as Markdown or Org-mode files and uses [[wikilink]] syntax with bidirectional links at the block level.
Logseq is an open-source personal knowledge-management application first released in 2020 by Tienson Qin. Like Obsidian (software) it is local-first — notes are stored as plain Markdown (or optionally Org-mode) files in a directory the user controls — but its interface is built around an outliner, in which every bullet is an addressable block, echoing the design of Roam Research. Pages are referenced with the wiki-style Page Title syntax, and bidirectional links exist at both the page and the individual-block level, with block references (((block-id))) allowing transclusion of bullets across pages. Logseq is released under the GNU AGPL and developed openly on GitHub; core features include daily journal pages, queries written in Datalog, a PDF annotation mode, a built-in flashcard system based on spaced repetition, and a graph view of the linked notes. A hosted sync service is offered as a paid add-on, but the application itself is free, and its local-first, plain-text design has made it a common choice for users who want a Roam Research-style outliner without a cloud lock-in.