Rare Build Hackathon - From Idea to Business in 10 Hours
Rare Build Hackathon
Hosted by Rare Founders × Mollie
One day. One room. 150 builders. Don't just build a product - build a business.
📅 11 July 2026 · 📍 The Ministry, London Bridge · 🕘 9:00 AM - 10:00 PM
What this is
A full-day, invite-only hackathon hosted by Rare Founders and Mollie. 150 of London's sharpest builders, designers, operators, and marketers in one room, forming teams on the spot, and shipping a real business by the end of the day.
This isn't a typical hackathon. We're not asking you to build a demo. We're asking you to build something people will actually buy.
You come up with the idea. You research it. You talk to real customers. You build it. You package it. You sell it.
By 7 PM, you'll pitch a product, a price, and proof someone wants it.
The challenge
Every team goes through the full startup loop in a single day:
Form the team → find your co-builders during the morning matchmaking.
Find the idea → no themes, no categories. You decide what's worth building.
Talk to real customers → leave the venue. Walk to the nearest coffee shop, office, high street, or co-working space. Talk to as many people as you can. Real validation, real conversations, real feedback. Bring the evidence back.
Build the product → engineers and designers build and package the solution while commercial team members validate, position, and sell.
Package it → name it, price it, position it, design the landing page, write the pitch.
Sell it → letters of intent, waitlist signups, pre-orders, paying customers. With Mollie's payment integration available on the day, you can actually take real money from real customers in real time. We'll count every form of validation. The strongest evidence wins.
Pitch it → defend your business on stage in front of judges who've built and backed real companies.
Thinking outside the box is the whole point. We know not every idea can generate revenue in a single day. What we want to see is teams doing everything they possibly can to prove the value. The teams that find the most creative ways to validate will stand out.
One rule: no gaming the system. Letters of intent must come from your actual target audience. Paying customers must be real. We're not interested in mates filling out forms. We're interested in evidence that strangers want what you've built.
Why this needs a full team
This format is impossible without all three disciplines on the team. That's not marketing copy. It's how the day actually works.
Technical → builds the product.
Design → packages it, names it, makes it feel real.
Commercial Sales Marketing → does the customer research, runs the outreach, secures the validation, writes the pitch, closes the sales.
If you've been on the commercial side wondering whether a hackathon is for you, this one is built around you. While the engineers and designers build, you're the one out talking to customers, testing positioning, securing the LOIs, and closing the sales. The team can't win without you.
Format
150 attendees, max. Applications reviewed. Not everyone gets in.
Teams form on the day. Matchmaking from 9:30. You leave the morning with a team or you don't build.
Minimum 2 per team, maximum 4. Ideal mix: one technical, one design, one commercial.
Open brief. Build whatever you want, for whoever you want.
You can leave the venue. Talking to real customers is encouraged. Bring the evidence back.
Mollie payment integration available for teams that want to take real payments on the day.
Submissions close at 7:00 PM. All teams submit. Judges review and the top 10 are announced.
Top 10 pitch on the main stage. 3-5 minutes each, including Q&A from the judges.
Every team must be ready to pitch. Even if you don't make the top 10, build pitch prep into your day. Plan for it.
Each business is judged individually. No artificial categories. The strongest businesses win.
Everything provided. Food, drinks, Wi-Fi, infrastructure credits, AI access, database templates, payment integration. Show up with a laptop.
How you'll be judged
Three judges. Three lenses. One winner.
Business viability - Is this a real business? Is there a market? Did you prove it? Caroline Frankum - Former CEO of Kantar, the world's largest user research company.
Investability - Would I put money into this team and this idea? David Gilgur - Partner at Blue Lake VC.
Technical execution - Did you actually build something? Is it solid? Could it scale? Fergus McKenzie-Wilson - CTO and Co-Founder at 60x.
Each judge weights what matters most for their lens, and we'll factor in what kind of business you've built when deciding how the criteria apply. A consumer product and a B2B SaaS prove value in different ways.
Mentors will be on the floor throughout the day to help teams unblock, sharpen their pitch, and answer questions across technical, design, and commercial challenges. Use them.
Agenda
9:00 AM Doors open. Breakfast, coffee, settle in
9:30 AM Matchmaking kicks off
10:30 AM Teams locked. Kick-off, intros, judges and mentors on stage
11:00 AM Build starts. Ideas, research, outreach, build, package, sell
1:00 PM Lunch
6:00 PM Dinner
7:00 PM Submissions close. Judges review
7:30 PM Top 10 announced. Pitches on the main stage, 3-5 mins each with Q&A
8:30 PM Winners announced, prizes handed out
8:30 – 10:00 PM Drinks, networking, debrief
10:00 PM Doors close
If you don't make the top 10, you stay, you watch, you drink, you network. The day doesn't end at 7.
Why apply
You'll meet people you'd never normally meet. Ten hours, shoulder-to-shoulder, with people you didn't know at 9 AM.
You'll build a real business in a day. Not a demo, not a deck. A product with customers attached.
You'll pitch in front of judges who matter. Even if you don't make the top 10, the right person seeing your work is worth the day.
You'll learn what it actually takes to ship. Most people never get this compressed.
You'll walk out with a network, not a tote bag. Past Rare Founders teams have gone on to raise, co-found, and hire from each other.
You'll have fun. Free food, free drinks, free infrastructure, and 150 people who chose to spend their day building.
Apply
Register to apply. Applications close is 6th of July. Reviewed on a rolling basis. Spots go fast.
👉 Spots are limited - sign up now.
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About Rare Founders
A founder-led community connecting early-stage founders, operators, and investors through curated events across London - open mics, roundtables, and Demo Days. Sign up to our weekly newsletter for handpicked startup events and opportunities.
About Mollie
Mollie is a leading European financial services platform, trusted by over 250,000 businesses to get paid and manage their money effortlessly. Join Mollie Community in Discord.
💥 Get better connected with Sophy
Sophy is your networking companion built for founders, investors, and operators. See who's in the room, add notes to your contacts, set follow-ups, and search your entire network - so no connection ever slips through. Join the waitlist: GetsophySoPhy — Never Lose a Contact Again
Want to sponsor the event and get exposure with hundreds of businesses? Please email [email protected]
A Huge Thanks To Our Sponsors & Partners!
Safety Partner
Safespace Plus is helping us to foster a safe and inclusive environment at our events. Check out our Code of Conduct so you are aware of what kind of behaviour is not allowed at our events.
Venue Partner
Hosted at The Ministry - Borough’s iconic creative members’ club and workspace, built by the team behind Ministry of Sound. Set inside a beautifully restored Victorian printworks, it features stylish lounges, studios, a gym, a buzzing bar, and everything designed for founders and creators to collide. With flexible day passes, wellness spaces, great coffee and a culture-driven vibe, it’s the perfect home for bold ideas and unforgettable events.