accounted
Hackathon · Saturday 5 September 2026

Build a CompanyOS.

Your backoffice, on autopilot. One Saturday in Stockholm to build the thing that does the recurring work while you sleep, on top of a ledger where Swedish bookkeeping law is enforced by the database. We are in the room all day answering questions about how the machinery works.

A team building around a table, halftone rendering
When
Saturday 5 September 2026, 10:00 until late
Where
Sting, Stockholm, and remote over Discord
Cost
Free. Lunch, dinner and drinks on us
After
A live jazz trio and a bar, from 20:00

The premise

A company runs on work nobody wants to do.

Bookkeeping, invoices, supplier bills, payroll, VAT, the monthly numbers. Today a founder does it by clicking through five systems that were designed for a person with a mouse. A CompanyOS is what you get when an agent does that work instead and a human only approves it.

The reason nobody has built one is that the write path has to be safe. In Accounted the legal rules are Postgres triggers, not application code: an entry that does not balance cannot be written, a posted voucher cannot be edited, voucher numbers are atomic and sequential. That is the part we already built. The rest of the operating system is what you build on Saturday.

Four tracks

What you can build.

01

The month that closes itself

One recurring cycle, end to end, with no human in the middle. Reconcile the month, chase the missing receipts, draft the VAT return, then stop at the approval queue and wait. Every write an agent makes is staged for a human, so you can let it run hard without breaking anything.

02

The pipes that carry the data in

A backoffice is only on autopilot if the inputs arrive on their own. Your POS, your booking system, your bank, your time tracking, your inbox. The REST API has idempotency, dry-run and webhooks, so an integration that normally takes a week is a day's work here.

03

The parts that are not accounting

Onboarding an employee, a supplier, a contract, an expense policy, a price change. The ledger is one organ, a CompanyOS is the body. This is the widest track and the one most likely to produce something nobody has built yet.

04

The screen that lets you watch it run

Nobody trusts an autopilot they cannot see. A dashboard, a display in the hallway, a Discord bot that reports what it did overnight, a voice interface that answers what a month cost. Trust is a UI problem as much as an engineering one.

Ignore the tracks if you have a better idea. They exist so nobody stares at an empty screen at 11:00. The API and MCP docs are up already if you want a head start: API and MCP, and the source is on GitHub.

Why we are doing this

Most accounting systems charge you for the privilege of building on them.

Our API and our MCP server cost nothing and need no partner application. The source is open under AGPL-3.0. The only thing missing is more people building on it, so we are setting aside a day, feeding you, and sitting in the room to answer questions in person.

What you build is yours. If you want it in our open registry we will do that together after the demos and help make it runnable for other people. If you would rather keep it to yourself, that is completely fine too.

The day

One demo, then a band.

No judges, no scoring, no pitch competition. Everyone who shows something that runs gets a contributor tee, and it is not for sale.

We are also not throwing you out at 20:00 with a cold slice of pizza. Lunch and dinner are on us, the bar opens after the demos, and a live jazz trio plays into the evening. Come for the building, stay for the part where you actually talk to the people you just built next to.

  1. 09:30Doors open. Coffee.
  2. 10:00Thirty minutes on the API, the MCP server, and how to get a test company with real data in it.
  3. 10:30Team forming, for anyone who wants a team.
  4. 11:00Build.
  5. 13:00Lunch, on us.
  6. 18:00Hands off keyboards.
  7. 18:15Demos. Three minutes per team, running code, no slides.
  8. 19:30Dinner and the bar opens.
  9. 20:00Live jazz. Stay as long as you like.

Bring

Four things, one of which is nothing.

  1. 01A laptop and a charger.
  2. 02An account on accounted.se. The free tier covers the whole day.
  3. 03Your own AI subscription if you have one. Claude, Cursor, Codex, whatever you run.
  4. 04No idea. Turning up empty and joining a team on the day is completely normal.

Sign up

Take a seat at Sting.

Registration runs on Luma, so the calendar invite lands straight away and you get a reminder before the day. We need a rough headcount to order the right amount of food, so if something comes up at the last minute, cancel there and the seat goes to someone else.

Questions? Ask in our Discord

Box not loading? Sign up on Luma directly