In Brief:
- Arbitrum started its online Buildathon on Sept. 14. Early-stage teams have three weeks to compete for $115K in prizes and grants.
- The winners get guaranteed spots at the in-person Founder House in Singapore on Oct. 23-25, where another $300K in prizes and grants is up for grabs.
- Robinhood Chain co-sponsors the program, and at least one podium spot in each of the Buildathon’s two prize tracks is reserved for a project building on it.
Arbitrum’s online Buildathon is underway. It’s the first phase of the Open House Singapore founder program, and early-stage teams are competing for $115K in prizes and a place at the network’s in-person Founder House in Singapore.
“Our online Buildathon program kicks off today,” Arbitrum said in a post on X announcing the start.
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 to Oct. 4. In that time, teams will “sharpen their ideas, MVPs and prototypes” and “get technical, product and GTM support,” Arbitrum said.
How the money splits
The $115K comes in three parts. The top three Buildathon teams split a $70K main prize pool, and at least one of those three places is reserved for a Robinhood Chain project.
A separate Promising Products track pays $15K, shared among its top three winners. It covers new products in frontier areas such as AI agents and new financial primitives. At least one spot there is also held for a Robinhood Chain team.
The Arbitrum Foundation has set aside the remaining $30K in USDC as grants. Winning teams receive them on a case-by-case basis.
Prizes don’t all arrive at once. Outside the Promising Products track, prize money is paid half upfront and half through milestone-based payouts.
The Singapore phase
Every Buildathon winner gets a confirmed seat at Founder House, which runs Oct. 23-25 in Singapore. On the third day, winners are announced and teams pitch live.
Founder House has its own pool of up to $300K in grants and prizes. Its tracks are 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 offers $120K in prizes, split among three teams building on Arbitrum and Robinhood Chain.
The two phases are independent. Teams can apply to either or both. Teams that don’t come through the Buildathon need an existing product or prototype to apply for Founder House.
Founder House targets projects in AI, DeFi, tokenization, payments, privacy and consumer crypto. Mentorship there covers product development, fundraising, technical infrastructure and go-to-market strategy.
What the Buildathon covers
The online phase is aimed at teams building new financial applications on Arbitrum, and its frontier category names AI agents directly.
Workshops during 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 serves as the Southeast Asia hub of Arbitrum’s 2026 global founder program. Together, the two Singapore phases put $415K on the table, with the Arbitrum Foundation and Robinhood Chain jointly sponsoring the prizes and grants.
Robinhood Chain pledged $1 million to the 2026 Open House program in February. That money is spread across Buildathons in New York City, London, Singapore and Dubai.
Singapore comes after the New York and London editions. The New York Founder House ran March 6-8.
In an earlier round, 350 builders took part in the online Buildathon and submitted 278 projects. Another 140 founders attended the in-person Founder House.
