Open Source Alternatives to Obsidian

Obsidian already stores notes as local Markdown files, but the app itself is closed source, so you can’t audit or modify how it works, and its sync and publishing features are paid, proprietary add-ons. Logseq offers the closest match — a similar outliner and bi-directional linking model, fully open source, with notes saved as plain Markdown or Org files. Anytype takes a more Notion-like block-and-database approach while still keeping data local-first and syncing peer-to-peer or through self-hosted infrastructure — note that unlike Logseq and Joplin, Anytype’s client apps are source-available rather than fully open source, so you can read the code but not redistribute it under the same terms. Joplin trades the graph-and-backlink model for a simpler, encryption-first Markdown note app with flexible sync options including Nextcloud and WebDAV. Logseq and Joplin are both fully open source, so you can verify exactly how your notes are stored and synced instead of trusting closed source code.