The best open source alternative to Obsidian is Logseq. If that doesn't suit you, our users have ranked more than 100 alternatives to Obsidian and loads of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Obsidian are Zettlr, Joplin, Notesnook and Standard Notes.
Workspace with end-to-end encryption, zero-knowledge security, rich notes, private journal, encrypted file storage, password management, cross-platform browser access, open-source cryptography, optional Pro features, and no recurring subscription fees.
United States
Local-first, privacy-focused notebook supporting Markdown and Emacs Org mode. Offers offline use, encrypted backups, plugin extensibility, LaTeX support, real-time collaboration, and hierarchical organization for personal knowledge management.
United States
Unified writing platform offering note-taking, easy citations with Zotero integration, LaTeX/Word templates, snippets, themes, dark modes, code highlighting, multi-language support, and knowledge management with Zettelkasten for seamless writing from notes to books.
Germany
EU
Open source app for managing notes and to-dos with Markdown support. Syncs seamlessly across devices using services like Dropbox and OneDrive. Offers end-to-end encrypted synchronicity, offline access, rich import/export options, and a Web Clipper for browsers.
FranceEU
Offers open-source, end-to-end encrypted notes with device-based privacy, cross-platform support, private vault, secure sync, offline access, markdown editor, exports to multiple formats, automatic backups, organizational tools, and strong encryption.
Pakistan
Secure note-taking app with end-to-end encryption, unlimited syncing across all platforms, offline access, detailed organization through tags, strong passcode and biometric protections, and premium features like encrypted files, themes, web clipper, super note types, and hardware key support.
United States
The original trilium is transfered to this repo by its owner and the app continues to develop here as stated here: https://github.com/TriliumNext/Trilium
Open-source workspace offering complete data control, deep customization via themes, plugins, and templates, native multi-platform support using Flutter and Rust, offline access, privacy features, collaborative tools, and easy extensibility for all users.
Singapore
Hierarchical note-taking software that is free, open-source, cross-platform. Features include rich text, syntax highlighting, multi-level lists, embedded files, customizable interface, code execution, PDF export, spell check, images & tables, and comprehensive project management support.
Cloud-based, open-source note-taking app supporting plain text notes, lists, and ideas with real-time sync, multi-device support, version history, markdown, tagging, collaborative editing, no ads, and free registration required for all cloud features.
United States
CryptPad is a private-by-design alternative to popular office tools and cloud services. All the content stored on CryptPad is encrypted before being sent, which means nobody can access your data unless you give them the keys.
FranceEU
SiYuan is a desktop Markdown Block-Reference and Bidirectional-Link note-taking application. Support fine-grained block-level reference and Markdown WYSIWYG.
China
Desktop note app stores plain markdown files with YAML, supports offline-first use, integrated Git repositories for full history, native Claude AI and Codex CLI integration, open source, portable data, keyboard-driven interface, no proprietary lock-in.
ItalyEU
