A hackathon is an event where people build something in a fixed amount of time, then show what they made. Most projects are software, such as an app, a website or a quick prototype, but some events focus on hardware, data or design.
The word mixes “hack” and “marathon”. One of the first recorded hackathons was run by the OpenBSD software project in Calgary in June 1999.
How a hackathon works
Most hackathons follow the same pattern:
- Kick-off. The organisers explain the theme or challenges, the rules and the timings.
- Building. People work on their own or in small teams. Mentors are often around to help.
- Demos. Everyone shows what they built, usually in a few minutes. Some events have judges and prizes.
How long does a hackathon last?
Anything from a few hours to a whole weekend. We found 135 London hackathons between October 2025 and October 2026. About three in four finished the same day, and about a third started at 5pm or later. Around one in four ran into a second day or longer.
Types of hackathon
- Hack nights: a few evening hours, often informal.
- Buildathons and build days: the same idea, usually with more focus on shipping something than on winning.
- Company hackathons: run by a company, either for its own staff or publicly, to get developers building with its product.
- Student hackathons: run by universities and student societies, often over a weekend.
- AI hackathons: focused on building with AI models and tools. More than a quarter of the London hackathons we found had “AI” in the name.
Who runs hackathons, and why?
Companies use them to get developers trying their tools, to meet people they might hire, or to give their own teams time to test new ideas. Universities and communities use them to help people learn, meet each other and build a portfolio. Some focus on a cause, such as a charity or a local problem.
Do you need to code?
No. A team also needs people who understand the problem, design the screens, test what works and present the demo. Plenty of people go to their first hackathon on their own. Our guide for beginners covers what to expect and how to prepare.
What do you get out of it?
Something you built, new skills and people to build with again. Some events also have prizes; the event page will say what’s on offer and who owns what you make.
Find one in London
Browse upcoming hackathons in London, updated every morning. If you’d like to run one for your company, Ramen Club organises hackathons at Ramen Space in Dalston.
Charlie Ward runs Ramen Club and Ramen Space, a founder coworking space in Dalston that runs hackathons.