The foundation published details in its Builder's Block developer newsletter on January 19, 2026, confirming that New York City, Dubai, London, and Singapore will each host a stage of the Open House program. The combined prize pool reaches $800,000, more than eleven times the $70,000 awarded during the India edition of the program in 2025. ArbOS Dia, designated version 51 of the Arbitrum operating system, had already gone live on January 8, eleven days before the newsletter published.

Open House Targets Founders, Not Weekend Builders

The foundation is positioning Open House 2026 as something different from a standard hackathon. The program combines an online buildathon phase with an in-person Founder House component in each city.

"Open House is back! This time: $800k in prizes. Four global cities. Not a hackathon, not a hacker house, but a global program built for founders who are serious about shipping, not just weekend builders," the @ArbitrumDevs account posted on X when announcing the program.

New York ran its online buildathon from February 5 through February 26, with an in-person Founder House held March 6 through 8. Dubai follows with its phase running April 23 through May 14. London and Singapore dates had not been confirmed as of the newsletter's January 19, 2026 publication; readers should verify current status directly with the foundation.

A Network Upgrade That Changes Fee Behavior

ArbOS Dia overhauled the fee pricing mechanism that governs transaction costs on Arbitrum One. The previous system used a single gas target and one adjustment window to calculate gas prices. The new system uses six target-and-window pairs, where short windows absorb sudden demand spikes and longer windows set the baseline. The result is a multiplication of all six outputs rather than a single averaged signal, which suppresses the sharp fee spikes that tend to hit users during high-demand events like token launches or NFT mints.

Post-activation data shows the practical effect. At roughly 130 million gas per second of demand, peak gas prices under the new algorithm run approximately 98% lower than the old system produced. Arbitrum also recorded a throughput of around 910 million gas per second in the period following activation, which the foundation describes as about 2.4 times the capacity of Base and roughly 15 times that of Ethereum mainnet. The minimum L2 base fee did rise slightly, moving from 0.01 gwei to 0.02 gwei, but median gas at peak demand measured around 2.12 gwei.

ArbOS Dia also introduces multi-resource metering: the State Transition Function now tracks computation, storage access, storage growth, and history growth as separate resources rather than blending them into a single gas signal. This architectural change gives developers and protocol teams more precise visibility into what their contracts actually consume. The upgrade additionally adds interop token support for Arbitrum Orbit chains, enabling mint and burn of native gas tokens compatible with LayerZero OFTs, xERC20s, native USDC, and native USDT (USDT0), a capability with direct relevance for builders constructing stablecoin payment rails.

The upgrade also adds support for the secp256r1 elliptic curve, aligning Arbitrum with Ethereum's Fusaka upgrade. In practical terms, this allows users to sign transactions using Face ID, Android Keystore, or FIDO2 hardware keys. Seed phrase management has long been identified as a key barrier to non-custodial wallet adoption, particularly in markets where users are accessing crypto for the first time on mobile devices.

Regional Implications for Builders Outside North America

For developers in South Asia, Southeast Asia, and the Gulf region, the program structure has some practical advantages. The online phase runs before each city's in-person event, meaning builders can participate in the early competition stages without covering travel costs. The ArbiFuel gas credit program, which ran through January 31, 2026 and has since concluded, provided up to $10,000 in gas credits and coverage for up to one million transactions per team, effectively removing early infrastructure costs during its availability period.

Singapore's inclusion positions the program for builders from Vietnam, Indonesia, the Philippines, and India. Dubai serves as an entry point for the Gulf corridor and the Indian diaspora tech community concentrated in the UAE.

For African developers, ArbOS Dia carries particular relevance. The passkey authentication feature is especially meaningful on the continent, where most crypto users access applications on Android devices and seed phrase management creates significant friction. Predictable, low fees also matter more in markets where users are transacting smaller amounts and fee spikes represent a proportionally larger cost. TechCabal has reported that 18 blockchain ecosystems are actively competing for African Web3 developer mindshare, with Arbitrum named alongside Ethereum, Solana, and Polygon as leading contenders. The Arbitrum HackerBoost program has already upskilled more than 450 African builders, producing seven new products in the process, two of which were production-ready at time of reporting. Burstek DAO manages and distributes foundation grants of $20,000 to $150,000 to Africa-focused Web3 projects. The interop token support introduced in ArbOS Dia, including native USDC and USDT0 compatibility on Orbit chains, adds direct utility for African fintech builders constructing stablecoin payment infrastructure.

Developer Tooling and Security Subsidies Round Out the Ecosystem Push

Alongside the network upgrade and founder program, the foundation released Stylus SDK v0.10.0 for developers building smart contracts in Rust, C, and C++. The update adds multi-contract workspace support, allowing teams to manage several contracts in a single repository with shared interfaces. A companion library called stylus-tools supports programmatic deployments, activations, and verifications, which matters for larger protocols running continuous integration pipelines.

The foundation also released x402 v2, introducing standardized network identity and EIP-712 typed data support for developers building payment and identity infrastructure on Arbitrum.

The foundation's $10M ARB audit subsidy program reached its first approvals, with 11 of 81 applicants cleared in Phase 1. Approved auditors include Trail of Bits, OpenZeppelin, and Certora. Professional security audits typically cost between $50,000 and $200,000 or more, a barrier that puts them out of reach for early-stage teams.

Market Context

ARB, the network's governance token, was trading around $0.10 to $0.11 at the time of the newsletter's publication, down roughly 27% over January 2026. Circulating supply stood at approximately 5.2 billion tokens out of a 10 billion total, giving a fully diluted valuation of around $980 million. A $19.6 million ARB unlock occurred on January 16, and a larger unlock of roughly $92.6 million is scheduled for March 16, two days from publication.

On-chain, Arbitrum held approximately $2.1 billion in total value locked as of early March 2026, reflecting current conditions at the time of this article's publication rather than conditions at the time of the underlying January newsletter. This represents about 30.9% of L2 DeFi TVL according to DefiLlama. Base, operated by Coinbase, held approximately 46.6% of the same market and was the only L2 to turn a profit in 2025, earning approximately $55 million. A 21Shares report published earlier this year noted that most Ethereum L2 networks may not survive 2026 as activity consolidates around a small number of players, specifically Base, Arbitrum, and Optimism. The combination of technical upgrades, global founder programming, and subsidized security infrastructure suggests Arbitrum is prioritizing long-term developer retention as that consolidation plays out.