Hackathon In 2 weeks
November
Friday
to Sun 15 November 2026 · London time
You sign up with the host. foundercal only links to it.
Most people carry startup ideas around for years. They research them endlessly, refine them, mention them at parties, and never find out whether anybody wants them.
The 48-Hour Startup Challenge changes this:You'll arrive Friday with an idea, or nothing at all. You'll leave Sunday with customers who have paid you or submitted a pre-order.On Friday we send you into London to ask somebody for one pound. No pitch, no product, no plan. Just you, a stranger, and the most uncomfortable sentence you've said in a while.By Sunday you'll be selling your real offering to real customers, and wondering why the pound felt so hard.
How it works
You'll be in small teams, taking challenges that land in a WhatsApp group all weekend. Some are ridiculous games that cost you nothing but your dignity. Some are the real work: who it's for, what to charge, what people actually want. Points come from money you actually collect, and scores are tracked on a live leaderboard.Most of it happens out in the city. You cannot find out what people will pay for while sitting at a laptop, and we won't let you try.No judges, no demo day, no investors. Someone buys or pre-orders from you, or they don't, and that's the only verdict that counts.
The weekend
The challenge runs all weekend. You'll need to join three in-person sessions at UCL School of Management, One Canada Square, Canary Wharf. In between, you're free to roam London completing the challenges we share on WhatsApp.
Friday
5pm - 5.15 pm · UCL School of ManagementArrivals5.15 pm to 7 pm · UCL School of ManagementOpening and "Off the Record" fireside chat with Joel Perlman, co-founder of OakNorth.
8 pm - 9 pm · Anywhere in LondonTeams start working on challenges
Saturday
10am to 1pm · UCL School of ManagementKick-off and speed workshop on building with AI. The minimum needed to make a sale, not the whole product.1pm onwards · Anywhere in LondonKeep completing challenges out in the city
Sunday
1 pm to 5 pm · Anywhere in LondonKeep working on challenges.5pm to 6pm · UCL School of ManagementWrap-up and winners announced.
All sessions above are required. Everything in between runs on WhatsApp, but the sessions are where teams form, challenges are set and results are counted. Miss one and you're out of the game. Between sessions, expect to be out selling, not resting.
You need: - a phone- a laptop- a free wekeendYou don't need: - an idea- a co-founder- a deck, or a plan.Teams form on Friday. Recruit a team around your idea or join one.
Our guest: Joel PerlmanJoel started his first company, Copal Partners, in 2002 with $60k. Over 12 years he and his co-founder Rishi Khosla grew it to 3,000 people across 12 markets, then sold it to Moody's in 2014, returning more than 200x to seed investors. In 2015 they founded OakNorth, a bank for entrepreneurs, which has since lent around $20bn to businesses in the UK and US and reached annual profits of around £215m. On Friday he'll talk openly about what it took, off the record.
Your host: Maiko SchaffrathMaiko has run accelerators in London, San Francisco and New York, and teaches entrepreneurship at Imperial College London. He taught customer development on UCL's MSc Entrepreneurship from 2018 to 2023, a programme he graduated from himself.He's coached hundreds of startups and personally built and scaled startups and their software products from 0 to $1M+ in annual revenue.Our partners:The venue is kindly provided by UCL School of Management
Full text on Luma .
Level 38 and Level 50, One Canada Square, Canary Wharf Estate, London E14 5AA, UK
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Founders pitch
Investors in the room