Trilium Notes

Trilium Notes is a free, open-source, cross-platform note-taking application focused on building large personal knowledge bases. Notes are arranged in a tree of arbitrary depth, and a single note can be cloned into several places in the tree, which lets you organize the same material along different lines without duplicating it.

The editor is a rich WYSIWYG one with tables, images, math and Markdown autoformatting, and there is also support for source code notes with syntax highlighting. Navigation relies on fast jumps between notes, full-text search and note hoisting. Notes are versioned automatically, and attributes can be used to organize, query and script notes. The interface is available in several languages, and built-in documentation opens with F1.

The project, now maintained as TriliumNext, is AGPL-3.0 licensed and built with TypeScript and Electron. It provides desktop builds as well as a server setup with Docker, so you can keep your notes on your own hardware. Stable releases are recommended, with nightly builds available for those who want the newest changes.