Arbitrum’s Open House NYC Online Buildathon attracted 512 builders from more than 40 countries during a three-week competition focused on developing applications across the ecosystem. The program ran from February 5 through February 26, 2026, with participants building across DeFi, gaming, social applications and DePIN using Arbitrum infrastructure.
According to the Arbitrum Foundation’s official recap, the competition combined technical workshops with founder-oriented sessions covering product development and go-to-market strategy. The online Buildathon offered $30,000 in prizes while creating a pathway into subsequent mentorship and the in-person Founder House in New York.
Arbitrum Rewards Three Winning Projects
Projects had to deploy on an Arbitrum chain to qualify, including Arbitrum One, Arbitrum Sepolia or an Orbit chain. Builders could use Solidity or Stylus-compatible tooling and were permitted to submit either new products or existing projects adapted for the ecosystem. Entries were evaluated around technical execution, product potential, innovation and their ability to solve practical market problems.
Tilt Protocol won first place and $15,000, followed by Fangorn with $10,000 and EqualFi with $5,000. The three winning teams advanced from the online competition into Arbitrum’s wider founder-support pipeline, which included direct technical assistance and additional opportunities for grants and mentorship.
The Buildathon formed the online portion of the broader Open House NYC initiative. The subsequent Founder House took place from March 6 to March 8, attracting 88 selected teams from 473 applications, with 55 projects ultimately submitting builds. The in-person phase significantly expanded the available funding, with $340,000 awarded through prizes and grants.
Open House Expands Beyond New York
Arbitrum designed Open House as a global founder program rather than a one-off hackathon. The NYC edition served as an early 2026 milestone in a broader initiative spanning additional locations including Dubai, London and Singapore, extending the model across multiple regional developer communities.
The program also illustrates how Arbitrum is using competitions as an acquisition funnel for developers rather than limiting support to short-term prize distributions. Builders can move from online development into in-person mentorship, ecosystem connections and potential funding, creating a longer path from prototype to deployed application.
The key milestone is therefore no longer registration or submission. Open House NYC has already completed its Buildathon and Founder House phases, turning the initiative from an upcoming developer competition into a completed cohort whose projects can now be measured by continued development and adoption.