SiYuan Note

SiYuan is a privacy-first, self-hosted, fully open-source personal knowledge management system that supports block-level referencing and WYSIWYG editing. Developed by Yunnan Liang (D.V) and launched in 2020, SiYuan has over 20,000 stars as of 2026 and has become one of the most popular note-taking tools in the Chinese developer community, with growing international adoption. SiYuan is designed as a local-first, privacy-respecting alternative to cloud-based note-taking tools like Notion and Obsidian, with all data stored locally by default and optional cloud sync. Key features include: block-level referencing (every paragraph, heading, list item, and code block is a uniquely addressable block with its own ID, enabling bidirectional linking and transclusion where changes to a block are reflected everywhere it is referenced), WYSIWYG Markdown editing (a rich text editor that renders Markdown in real-time, supporting headings, bold, italic, code blocks, math formulas via KaTeX, and tables), block types (supporting text, headings, lists, blockquotes, code, math, tables, embeds, dividers, super blocks for multi-column layouts, and custom blocks via plugins), SQL query (querying blocks via SQL through a built-in SQLite database, enabling complex searches and dynamic content blocks), templates (creating reusable block templates with variable substitution for structured note-taking), spaced repetition (flashcard review using the FSRS algorithm for active recall), PDF annotation (annotating PDFs with highlights and notes linked to knowledge base blocks), S3 and WebDAV sync (synchronizing data across devices via S3-compatible storage and WebDAV), end-to-end encryption (optional E2E encryption for cloud sync), data export (Markdown, PDF, HTML, and plain text export), plugin system (extending functionality with community plugins), and theme customization (light, dark, and custom CSS themes).