Platform WatchJune 25, 2026via Hacker News
Show HN: OpenKnowledge – open source AI-first alternative to Obsidian/Notion
Why it matters
A new productivity layer built for AI-native workflows. OpenKnowledge positions itself as the markdown-first alternative to Obsidian/Notion that treats LLM agents as first-class citizens, not bolt-ons. This matters to founders and teams building on Claude/Cursor who need collaborative, agent-aware knowledge management.
Key signals
- MacOS app + CLI launch
- Direct integrations with Claude, Codex, Cursor
- Open source (GitHub: inkeep/open-knowledge)
- WYSIWYG markdown editor with bidirectional ProseMirror-to-markdown conversion
- Dual-observer CRDT for collaborative agent transparency and version history
- Built-in MCPs, RAG, and 'AI Second Brain' scenarios
- Fully local, no cloud lock-in (git/GitHub for sync)
- Tech stack: Tiptap/ProseMirror, CodeMirror, Yjs, Electron, Orama, remark/rehype
The hook
Not a plugin. OpenKnowledge embeds Claude, Codex, and Cursor agents directly into markdown editing—side-by-side, fully local, fully open source.
Hi HN, Nick here. We’re launching OpenKnowledge (https://openknowledge.ai/), a “what you see is what you get” markdown editor that has direct integrations with Claude, Codex, and Cursor. Available as MacOS app or CLI. Fully free/local and OSS (
We built this because we wanted a “Google docs” like experience for writing and sharing markdown files across our team. Obsidian is the best alternative we tried, but found it doesn’t have a true “what you see is what you get” UI and it didn’t integrate well with Claude/Codex outside of community plugins.
So we built OpenKnowledge. It takes shape as:
1. A MacOS app with a file navigator, the WYSIWYG editor, and link explorer.
2. Integrations with the Claude, Codex, and Cursor desktop apps. The agents can open an OpenKnowledge editor within their embedded web browsers for a side-by-side experience.
3. Built-in mcps, skills, and RAG for LLM-wiki and “AI Second Brain” scenarios + spec writing
4. An embedded terminal and CLI for TUI-first users
OSS stack includes: Tiptap/prosemirror, CodeMirror, yjs (CRDT), Electron (MacOS app), Orama, remark/rehype/micromark/mdast, @pierre/trees
On the architecture side, the interesting eng. challenges included:
1. A pipeline to convert ProseMirror to markdown in a bidirectional lossless way. ProseMirror uses ASTs, which are not designed to have byte-fidelity.
2. A dual-observer CRDT to keep the ProseMirror and markdown state in-sync.
The CRDT + git also power a collaborative experience that shows what Agents are doing in the markdown, have undo/redo, and version history. The “Share” and cloud-sync functionality are geared for team collaboration. They feel “no-code” but leverage git/GitHub under the hood, which also means data stays fully private.
In that spirit, we made OpenKnowledge open source for anybody who’s curious or who’d like to contribute.
We’re actively thinking about plugins/extensibility and what’s next. If you have suggestions or feedback, would love to hear it.
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