Builder's Block #021: Robinhood Chain Mainnet Live on Arbitrum & Founder House London Winners
⚙️ Robinhood Chain Mainnet is Now Live on the Arbitrum Platform
💳 ZeroDev Launches a New Wallet
🇬🇧 Founder House London Concludes with $300K Awarded
📣 Announcements
Key updates from the Arbitrum ecosystem and Foundation.
Robinhood Chain Mainnet is Live
The launch of Robinhood Chain enables a more customized infrastructure designed to satisfy precise performance, security, and regulatory requirements. This environment establishes a robust foundation for the integration and development of decentralized financial primitives.
Introducing ZeroDev Wallet
ZeroDev Wallet is an embedded wallet built on ZeroDev’s programmable account infrastructure. It gives teams one stack for wallet creation, signing, smart account execution, gas sponsorship, session keys, policies, recovery options, and transaction orchestration.
Meet the Winners of Founder House London
From more than 490 registrations, 140 founders were selected to join Founder House London for three days of targeted sessions and iteration on product-market fit and go-to-market alongside mentors from across the Arbitrum ecosystem. By the end of the program, teams had submitted 64 projects competing for a share of $300,000 in prizes and grants.
📚 Learn & Build
New learning drops and hands-on resources from across the Arbitrum ecosystem.
Predictable Fees for Onchain Agents
As agentic commerce grows, predictable fees become increasingly important.
This article breaks down why predictable fees matter for agentic commerce, how gas pricing works, and how Arbitrum’s dynamic pricing is evolving to support this next wave of onchain demand.
Build Your First Robinhood Chain App
Want to get started in building on the Robinhood Chain? This article from @hummusonrails features a full walkthrough from code design to final deployment of your first dApp on Robinhood!
Arbitrum Supports x402 and MPP For Agentic Finance
Developers now have two new pathways for building agentic payment and settlement flows on Arbitrum. Arbitrum is supported by Coinbase’s hosted x402 facilitator, and Offchain has published arbitrum-mpp, an open-source implementation for making payments over MPP on Arbitrum.
How Smart Accounts Give Onchain AI Agents Safe Permissions
Agents need the ability to act. They also need boundaries. Smart accounts make that possible by moving permissions, policy, and enforcement to the account layer.
🔦 Ecosystem Highlights
Fresh launches and standout threads from around the Arbitrum ecosystem.
$800K in Revenue in the Last 7 Days
Robinhood Chain generated more than $800K in revenue in the last 7 days, annualizing to $42M at this rate.
Introducing Swaps by Variational
Variational just launched Swaps, bringing Wall Street's widely used trading infra onchain with institutional liquidity for tokenized markets. A big step for @variational_io toward bringing TradFi into the programmable economy.
Rialto Goes Live on Robinhood Chain
We’re excited to welcome @rialto_xyz, an onchain exchange for trading and borrowing against tokenized equities, crypto and real-world assets, launched on the Robinhood Chain.
Prism is Live on Arbitrum
Arbitrum is building the finance-native platform for the programmable economy. Prism is where the pieces of Arbitrum’s financial stack start coming together.
🛠️ Dev Tooling & Infra
Updates to SDKs, CLIs, and developer workflows across the stack.
ZeroDev Wallet SDK
What does a smart-account-first embedded wallet SDK actually unlock?
ZeroDev breaks down 5 product flows to build with the ZeroDev Wallet SDK.
🗓️ Events
Workshops, builder and founder programs, and ecosystem meetups to watch.
Recap: Founder House London
If you’re a founder who missed the ultimate in-person mentorship experience, here’s a look at what went down at Arbitrum Founder House London 🇬🇧
We've brought teams together under one roof for a 3-day founder residency where they:
- Built new financial products across tokenized capital markets, collateral and risk infrastructure, payments, tokenized equity, agentic finance and yield bringing products onchain via Arbitrum One and the Robinhood Chain
- Refined their product & GTM strategies
- Received mentorship from our ecosystem partners
- Competed for $300k in prizes
Catch the highlights. 👇🏻
To keep up with upcoming builder programs, funding opportunities, and ecosystem updates, subscribe to the Builder Newsletter.
🧵 Forum & Community Discussions
What builders are debating and proposing this week.
[Constitutional] AIP: Ratification of Security Council Election Process Improvements
In September 2025, the ArbitrumDAO showed varying degrees of support for five Security Council Election process improvements via a temperature check. This updated temperature check aims to ratify the DAO’s support for the inclusion of four and omission of one of the originally proposed improvements, ahead of an on-chain vote.
ArbitrumDAO Factsheet: Robinhood Chain Mainnet Launch
Robinhood Chain went live on public mainnet on 1 July 2026, a dedicated Arbitrum chain settling to Ethereum, after a testnet that processed more than 200 million transactions.
