Builder's Block #012: Arbitrum NYC Open House Winners Announced & Mentorship Program Applications Now Open

📣 Announcements

Key updates from the Arbitrum ecosystem and Foundation.

Mentorship Program — NOW OPEN

Eight-week, equity-free program with structured sessions, mentors from top ecosystem projects, and a Demo Day with investors and top venture firms. Deadline: April 7th.
➡️ Apply For The Mentorship

Robinhood Chain Testnet: 4M Transactions in One Week

Developers are testing tokenized equities, lending protocols, and perps in a financial-grade sandbox. Robinhood commits $1M to Open House 2026, helping to fund a new generation of ecosystem builders. Mainnet is expected to arrive later this year later this year.
➡️ Start building on Robinhood Chain

Open House NYC Buildathon Winners Announced

Out of the 512 builders, three teams emerged victorious after rigorous evaluation:

Tilt Protocol - $15,000 prize
Fangorn - $10,000 prize
EquelFi - $5,000 prize

Congratulations to the winning teams! For those who don’t give up, keep building. You have plenty of opportunities within the Arbitrum ecosystem this year.
Read the Full Announcement

📚 Learn & Build

New learning drops and hands-on resources from across the Arbitrum ecosystem.

AI and Stylus: The Builder's New Toolkit

Accelerate your onchain development with AI thanks to a Claude Code Skill for Arbitrum dApp development. Find your path and innovate on agents with Stylus, ERC-8004 and x402.
➡️ Get the Claude Skill

More Resources to build AI Agents on Arbitrum

• ERC-8004 reputation, discoverability, and trust for AI agents are live on Arbitrum One and Sepolia.
  ➡️ ERC-8004 Tutorial

• x402 machine-to-machine payments with automatic USDC batch settlement, built on Arbitrum.
  ➡️ x402 Tutorial

Move Smart Contracts are now live on Arbitrum

Move smart contracts run on Stylus via the Move-to-WASM compiler, alongside Rust, C, and C++. Aptos and Sui devs: your skills transfer directly. We prepared an episode with Rather Labs to know what it unlocks for builders.
➡️ Watch the episode

🔦 Ecosystem Highlights

Fresh launches and standout threads from around the Arbitrum ecosystem.

Carbon Perp DEX Migrates from Base → Arbitrum

Carbon moved for one reason: Arbitrum's 250ms blocks. Carbon Solver, CLP, and the Momentum Program are all launching on Arbitrum.
➡️ Read the article

USD.AI: AI Infra Financing on Arbitrum

USD.AI have crossed another milestone, amassing a combined market cap of more than $650M. The protocol finances GPU-backed AI infrastructure through tokenized credit, with PayPal's PYUSD integrated as a reserve asset.
➡️ Explore USD.AI

Timeboost Hits $6.74M in Cumulative Fees

$6.74M in real fees from blockspace demand. 97% to Arbitrum DAO, 3% to the developer guild. For HFT builders: the express lane auction runs every 60 seconds.
➡️ Learn about Timeboost

🛠️ Dev Tooling & Infra

Updates to SDKs, CLIs, and developer workflows across the stack.

Nethermind's Execution Arbitrum Client is Now Public

Where it stands: full node execution processing over 300M Arbitrum One archive blocks, with Stylus smart contract support.
➡️ Open-Sourced in GitHub

Robinhood Chain Oracle Integration

Chainlink is live as Robinhood Chain's oracle provider. Builders can leverage Chainlink’s data, interoperability, and compliance standards to power advanced tokenization use cases.
➡️ Check the announcement

Increasing the Smart Contract Size Coming to Arbitrum

Contributors and developers share their opinions and proposals at the Arbitrum DAO forum, and requests are taken into consideration. From idea to reality, 96kb contracts coming to Arbitrum soon. Cudos to contributor @CupOJoseph.
➡️ Check the forum proposal

🗓️ Events

Workshops, hackathons, and ecosystem meetups to watch.

Open House NYC Founder House - March 6th, 2026

In-person Founder House for top buildathon teams. Build alongside mentors, get direct feedback, and pitch for funding.
➡️ Apply for Open House NYC

Fhenix & Arbitrum Cocktail Party in NYC

Join Fhenix and Arbitrum for an exclusive happy hour to kick off the Arbitrum Open House in NYC. If you're building with FHE, confidential compute, or privacy on L2, this is your room.
➡️ Register now

🧵 Forum & Community Discussions

What builders are debating and proposing this week.

DVP Quorum & Proposal Cancellation is Heading to an Onchain Vote

The initial temperature check has passed, and the quorum has shifted from total voteable supply, to delegated voting power (DVP), followed by an onchain proposal cancellation.
➡️ Read the proposal

Steven Goldfeder, CEO at Offchain Labs Features in Arbitrum Everywhere Series.

In the third episode of our Arbitrum Everywhere series, Steven Goldfeder, CEO at Offchain Labs, discusses how Arbitrum is emerging as the trusted independent platform that institutions such as Robinhood rely upon for long-term, scalable growth.
➡️ Watch here

Introducing ChainCraft: an AI-powered Game Creation

Following the completion of a successful Questbook grant, ChainCraft is emerging as an AI-powered platform where anyone can create, play, and own multiplayer games through conversations on Arbitrum.
➡️ Read the final report

That’s all from Builder’s Block #012. Thank you for reading, and keep building. Arbitrum Everywhere.