Best open-source alternatives to Obsidian

AFFiNE is an open-source workspace platform designed for writing, drawing, planning, and organizing knowledge in one place. It combines document editing and whiteboard-style canvas interactions, aiming to serve users who want a Notion- and Miro-like experience in a single product. The project emphasizes a local-first approach, so users keep data on their own devices while still getting real-time sync and collaboration across web and cross-platform clients. It also includes AI-assisted creation workflows, such as turning outlines into slides or summaries into mind maps, and supports self-hosting for teams or individuals who want more control over deployment and data.

Joplin is an open source note-taking and task management application aimed at people who want to organize a large volume of notes in notebooks and work with them in Markdown. It supports searching, tagging, editing, and importing content from Evernote or plain Markdown files, making it useful for users migrating from other tools or maintaining text-based note libraries. The project is designed with an offline-first approach, so data remains available on the user’s devices even without internet access. For those who want cross-device synchronization, Joplin can securely sync with cloud services such as Nextcloud, Dropbox, OneDrive, and Joplin Cloud using end-to-end encryption. It also offers full-text search, customization through plugins and themes, and companion apps across major desktop and mobile platforms.

Logseq is an open-source knowledge management and collaboration platform aimed at people who want a privacy-focused way to organize notes, tasks, and related information. It supports common note formats such as Markdown and Org-mode, and it emphasizes user control, longevity, and extensibility through plugins and themes. The README presents Logseq as suitable for students, professionals, and anyone managing personal or team knowledge workflows. It is available as a desktop application, has a web version for testing the DB version, and includes mobile apps. The DB version adds graph-based data, a new sync approach called RTC for real-time collaboration, and automated or SQLite database backup guidance because the feature set is still in beta/alpha.

SiYuan is a personal knowledge management system designed around privacy and local control. It targets individuals who want to organize notes and knowledge using block-based editing, fine-grained references, and a Markdown-based WYSIWYG workflow rather than a traditional document-only model. The project emphasizes a broad feature set that includes large-document editing, databases, flashcards, export options, snippets, OCR, and an API for extension and integration. It also has a wider ecosystem of companion apps and components for mobile, desktop, marketplace content, and data repositories, suggesting it is aimed at users who want a cross-platform knowledge workspace with both local and deployment-oriented options.