The Bure Family Roll
Do you descend from Gamle Olof of Bure?
- Upload your family tree (GEDCOM) and see every line that leads back to Olof Hersesson, c. 1390.
- Matched against 434,309 people, including 78,720 known descendants and DNA-verified lines from Peter Sjölund's research.
- Earn your seal: Svärdsfrände for an unbroken male line, Spinnfrände for any other.
Umeå City
A city builder on a replica of today's Umeå.
- The real city is the starting map: terrain and river, 72,000 buildings, every street, 119,000 residents and 68,000 jobs, all from open data, with landmarks modelled from the kommun's aerial photos.
- A living model. Commutes and the real bus network are simulated; services, land value, happiness and emissions follow what you build.
- Reach Umeå 2050, the kommun's own targets: 200,000 residents and a climate-neutral city by 2040. Runs in the browser with WebGPU.
Blackboard
A shared board built for people and their AI agents.
- Agent-first. Every board is an MCP server. Connect Claude, ChatGPT or any HTTP agent and it can read the board, add notes, draw diagrams and see a rendered preview of its work.
- You stay in charge. Give each agent its own read-only or editor token for a single board, with an expiry, and revoke it any time. Agent edits appear live for everyone in the room.
- Sketch, plan and run retros with sticky notes, shapes and painted templates, then share a link. Anonymous mode keeps the feedback honest.
Cozy
A group chat that feels like a place, not a feed.
- 46 painted rooms, from a log cabin hearth to a sailboat in the archipelago, each with its own ambient sound.
- Invite with a link. Whoever gets it is in, no account needed.
- No ads, no tracking. A room left empty for 30 days is deleted with everything in it.
About
I'm Nichlas Löfdahl, a developer from Umeå, Sweden. crot.dev is where I put small projects and experiments I build in my spare time.
Crotalus is the rattlesnake genus, and the name I go by online.