About Diffdown

What is This?

Diffdown is a real-time collaborative Markdown editor/previewer built on the AT Protocol (the tech that powers Bluesky).

Diffdown is decentralized; it stores documents as AT Protocol records on the document creator's PDS, not on the Diffdown server or some cloud provider.

I built Diffdown to learn AT Protocol, lexicons, and agentic engineering. Consider it a "pre-alpha" prototype. Because AT Proto does not support private records (yet), any documents you create will be visible to anyone with the URL (example).

About Me

I've worked in tech for a long time as a product manager and executive. These days, I'm a co-founder of Limeleaf Worker Collective, and an advisor to a few startups. Read about my journey building Diffdown on my Leaflet.

Technology

• Backend: Go, SQLite
• Frontend: Plain 'ole HTML, CSS, JavaScript
• Editor: ProseMirror with prosemirror-collab for real-time collaboration; Milkdown for Markdown
• Authentication: ATProto OAuth (any PDS)
• Deployment and hosting: Fly.io

Status

This is a prototype. Use at your own risk.

Important: Because AT Proto does not support private data (yet), any documents you create will be visible to anyone with the URL.

Expect bugs, breaking changes, and limited features.

However, any documents you create will be stored in your AT Proto account, so even if Diffdown goes away, you will still have your documents.

Contact

Feedback, bug reports, and feature requests are welcome. Reach out via Bluesky or check the GitHub repository.