SiYuan
Privacy-first personal knowledge management system
About SiYuan
SiYuan is an open-source, privacy-first personal knowledge management system that supports Markdown, block-level references, and bidirectional links. It works completely offline with optional end-to-end encrypted cloud sync, making it ideal for users who want full control over their data.
Pros & Cons
Pros
- Completely open source and self-hostable
- Strong privacy with local-first architecture
- Powerful block-level referencing system
- One-time lifetime pricing (no recurring fees)
- Rich content support including math, charts, and diagrams
- Active development with frequent updates
Cons
- Steeper learning curve than simpler note apps
- Cloud sync requires paid plan
- Smaller community compared to Notion or Obsidian
- UI can feel complex for casual note-taking
Key Features
Block-Level Editing
Edit and reference content at the block level, enabling granular knowledge organization and reuse
Bidirectional Links
Create two-way connections between notes for a networked knowledge graph
Full Markdown Support
Write in Markdown with support for math formulas, charts, flowcharts, Gantt charts, and more
Complete Offline Usage
Works entirely offline with local-first data storage for maximum privacy
End-to-End Encrypted Sync
Optional cloud sync with end-to-end encryption for secure multi-device access
Graph View
Visualize connections between notes in an interactive knowledge graph
S3/WebDAV Integration
Sync and backup via third-party services like Amazon S3 and WebDAV
Cross-Platform
Available on Windows, macOS, Linux, iOS, Android, and Docker
Pricing
- All core features
- Local-first storage
- Block editing
- Markdown support
- Offline access
- Graph view
- Everything in Free
- S3/WebDAV sync & backup
- Asset content search
- Third-party service integration
- Everything in Pro
- 8GB cloud storage
- Official cloud sync
- Cloud inbox
- Automatic backup
Best For
Personal Knowledge Management
Build a second brain with interconnected notes, bidirectional links, and graph visualization
Academic Research
Organize research papers, create references between concepts, and use math/chart support for technical writing
Privacy-Focused Note-Taking
Keep all data local with optional encrypted sync for users who prioritize data sovereignty
Technical Documentation
Create structured documentation with block-level editing, code blocks, and diagram support
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Featured In
7 Best Open-Source Note-Taking Apps for Knowledge Management (2026)
Best for privacy-focused individual knowledge management — SiYuan's block-level precision, one-time pricing, and FSRS flashcards make it ideal for researchers and learners building long-term personal knowledge bases
6 Notion Alternatives That Don't Lag on Large Workspaces (2026)
Best for researchers who need deep block-level linking with built-in spaced repetition — SiYuan's granular referencing and flashcard system create a unique learn-while-you-write workflow.