Zettlr is a free and open-source note-taking application that works with Markdown files.

[2][3] Internal links may be created between notes, which can be visualised as a graph, enabling its use as a personal information management system or digital Zettelkasten.

[10][11] Version 3.0 was released in September 2023, introducing a new logo as well as split view, multiple windows, pinned tabs, a status bar, and LanguageTool integration for spelling and grammar checking.

[12] Zettlr is built on Electron, as a cross-platform application that runs on Windows, Linux, and macOS.

[19] Zettlr integrates with reference managers such as Zotero, JabRef and Mendeley using CSL JSON or BibTeX files to enable inclusion of citations and bibliographies for academic writing.