In Brief:
- Arbitrum’s online Buildathon began on Sept. 14. For three weeks, early-stage teams will compete for $115K in prizes and grants.
- Every winner is guaranteed a place at the in-person Founder House in Singapore on Oct. 23-25. A further $300K in prizes and grants is available there.
- Robinhood Chain co-sponsors the program. In each of the Buildathon’s two prize tracks, at least one podium place is held for a project building on Robinhood Chain.
The online Buildathon from Arbitrum has started. It opens the Open House Singapore founder program. Early-stage teams are now competing for $115K in prizes and a seat at the network’s in-person Founder House in Singapore.
Arbitrum announced the launch on X: “Our online Buildathon program kicks off today.”
Our online Buildathon program kicks off today
Over the next 3 weeks, early-stage teams will:
> sharpen their ideas, MVPs and prototypes
> get technical, product and GTM support
> compete for $115K in prizes & spots to our in-person Founder House in Singapore
On top of that,@ArbitrumView on X ↗
The Buildathon runs from Sept. 14 through Oct. 4. Arbitrum said that during this time teams will “sharpen their ideas, MVPs and prototypes” and “get technical, product and GTM support.”
How the money splits
The $115K is divided three ways. The main prize pool is $70K, shared by the top three Buildathon teams. At least one of those three places is held for a Robinhood Chain project.
A separate Promising Products track is worth $15K, divided among its top three winners. It is for new products in frontier areas such as AI agents and new financial primitives. Here too, at least one place is kept for a team building on Robinhood Chain.
The remaining $30K, in USDC, is a grant allocation from the Arbitrum Foundation. Winning teams receive these grants on a case-by-case basis.
Not all prize money is paid at once. Except in the Promising Products track, winners get half upfront and the other half through milestone-based payouts.
The Singapore phase
All Buildathon winners are guaranteed a seat at Founder House, held in Singapore on Oct. 23-25. The third day brings live team pitches and the announcement of winners.
Founder House has its own pool of up to $300K in grants and prizes. It is split across a General Builder Track, a Robinhood Chain Founder-in-Residence Award, a Robinhood Chain Innovation Award, ecosystem grants, and dedicated support for promising projects in areas such as AI agents and new financial primitives.
The General Builder Track alone carries $120K in prizes. It is shared by three teams building on Arbitrum and Robinhood Chain.
The two phases are separate, so teams can apply to one or both. A team that does not arrive through the Buildathon needs an existing product or prototype to apply for Founder House.
Founder House is looking for projects in AI, DeFi, tokenization, payments, privacy and consumer crypto. Its mentorship covers product development, fundraising, technical infrastructure and go-to-market strategy.
What the Buildathon covers
The online phase targets teams building new financial applications on Arbitrum. Its frontier category names AI agents explicitly.
Workshops over the three weeks cover product development, go-to-market strategy, user experience, agentic commerce, wallet infrastructure and emerging market opportunities. Ecosystem partners provide technical and infrastructure support.
Background
Open House Singapore is the Southeast Asia hub of Arbitrum’s 2026 global founder program. The two Singapore phases together offer $415K. The Arbitrum Foundation and Robinhood Chain co-sponsor the prizes and grants.
In February, Robinhood Chain committed $1 million to the 2026 Open House program. That sum covers Buildathons in New York City, London, Singapore and Dubai.
Singapore follows the New York and London editions. The New York Founder House took place March 6-8.
In an earlier round, 350 builders joined the online Buildathon and submitted 278 projects. Another 140 founders attended the in-person Founder House.