SiYuan is a privacy-first personal knowledge management system, support fine-grained block-level reference and Markdown WYSIWYG. 🔮 Features Most features are free, even for commercial use. Content block Block-level reference and two-way links Custom attributes SQL query embed Protocol siyuan:// Editor Block-style Markdown WYSIWYG List outline Block zoom-in Million-word large document editing Mathematical formulas, charts, flowcharts, Gantt charts, timing charts, staffs, etc. Web clipping PDF Annotation link Export Block ref and embed Standard Markdown with assets PDF, Word and HTML Copy to WeChat MP, Zhihu and Yuque Database Table view Flashcard spaced repetition AI writing and Q/A chat via OpenAI API Tesseract OCR Multi-tab, drag and drop to split screen Template snippet JavaScript/CSS snippet Android/iOS/HarmonyOS App Docker deployment API Community marketplace