> ## Content Index > Fetch the complete content index at: https://blog.arbitrum.foundation/llms.txt > Use this file to discover other available public pages before exploring further. # Builder's Block #021: Robinhood Chain Mainnet Live on Arbitrum & Founder House London Winners - URL: https://blog.arbitrum.foundation/builders-block-021-robinhood-chain-mainnet-live-on-arbitrum-founder-house-london-winners/ - Published: 2026-07-16T12:57:12.000Z - Updated: 2026-07-16T12:57:52.000Z - Author: Arbitrum Foundation - Tags: Builder Newsletter 💡 ****What's Important This Week** ⚙️ 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 [![0626_Arbitrum_Robinhood_Mainnet_Blog_R4.png](https://storage.ghost.io/c/d4/cc/d4cc8040-691e-4dd2-8282-0c08d45fc5a8/content/images/2026/07/0626_Arbitrum_Robinhood_Mainnet_Blog_R4-1.png)](https://blog.arbitrum.io/robinhood-chain-mainnet/?ref=blog.arbitrum.foundation) 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. [ Read the Story ](https://blog.arbitrum.io/robinhood-chain-mainnet/?ref=blog.arbitrum.foundation) ### Introducing ZeroDev Wallet 0:00 /0:56 1× 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. [ Try It Now ](https://www.zerodev.app/blogs/introducing-zerodev-wallet?ref=blog.arbitrum.foundation) ### Meet the Winners of Founder House London [![0726_OpenHouse_London_FounderHouse_Recap_Blog.jpg](https://storage.ghost.io/c/d4/cc/d4cc8040-691e-4dd2-8282-0c08d45fc5a8/content/images/2026/07/0726_OpenHouse_London_FounderHouse_Recap_Blog.jpg)](https://x.com/arbitrum/status/2077728969030316338?s=20&ref=blog.arbitrum.foundation) 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. [ Meet the Winners ](https://x.com/arbitrum/status/2077728969030316338?s=20&ref=blog.arbitrum.foundation) --- ## 📚 Learn & Build *New learning drops and hands-on resources from across the Arbitrum ecosystem.* ### Predictable Fees for Onchain Agents [![predictable fees.jpeg](https://storage.ghost.io/c/d4/cc/d4cc8040-691e-4dd2-8282-0c08d45fc5a8/content/images/2026/07/predictable-fees.jpeg)](https://x.com/0xjesstech/status/2074444889119391775?s=20&ref=blog.arbitrum.foundation) 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. [ Read the Article ](https://x.com/0xjesstech/status/2074444889119391775?s=20&ref=blog.arbitrum.foundation) ### Build Your First Robinhood Chain App [![robinhoodapp.jpeg](https://storage.ghost.io/c/d4/cc/d4cc8040-691e-4dd2-8282-0c08d45fc5a8/content/images/2026/07/robinhoodapp.jpeg)](https://x.com/hummusonrails/status/2075150298419490847?s=20&ref=blog.arbitrum.foundation) Want to get started in building on the Robinhood Chain? This article from [@hummusonrails](https://x.com/hummusonrails?ref=blog.arbitrum.foundation) features a full walkthrough from code design to final deployment of your first dApp on Robinhood! [ Read the Article ](https://x.com/hummusonrails/status/2075150298419490847?s=20&ref=blog.arbitrum.foundation) ### Arbitrum Supports x402 and MPP For Agentic Finance [![x402 support.png](https://storage.ghost.io/c/d4/cc/d4cc8040-691e-4dd2-8282-0c08d45fc5a8/content/images/2026/07/x402-support.png)](https://blog.arbitrum.io/x402-and-mpp-for-agentic-finance-on-arbitrum/?ref=blog.arbitrum.foundation) Developers now have two new pathways for building agentic payment and settlement flows on Arbitrum. Arbitrum is supported by [Coinbase’s hosted x402 facilitator](https://docs.cdp.coinbase.com/x402/network-support?ref=blog.arbitrum.foundation), and Offchain has published [arbitrum-mpp](https://github.com/OffchainLabs/arbitrum-mpp?ref=blog.arbitrum.foundation), an open-source implementation for making payments over MPP on Arbitrum. [ Read the Article ](https://blog.arbitrum.io/x402-and-mpp-for-agentic-finance-on-arbitrum/?ref=blog.arbitrum.foundation) ### How Smart Accounts Give Onchain AI Agents Safe Permissions [![zerodev smart accounts.jpeg](https://storage.ghost.io/c/d4/cc/d4cc8040-691e-4dd2-8282-0c08d45fc5a8/content/images/2026/07/zerodev-smart-accounts.jpeg)](https://www.zerodev.app/blogs/how-smart-accounts-give-onchain-ai-agents-safe-permissions?ref=blog.arbitrum.foundation) 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. [ Learn More ](https://www.zerodev.app/blogs/how-smart-accounts-give-onchain-ai-agents-safe-permissions?ref=blog.arbitrum.foundation) --- ## 🔦 Ecosystem Highlights *Fresh launches and standout threads from around the Arbitrum ecosystem.* ### $800K in Revenue in the Last 7 Days [![revenue.jpeg](https://storage.ghost.io/c/d4/cc/d4cc8040-691e-4dd2-8282-0c08d45fc5a8/content/images/2026/07/revenue.jpeg)](https://tokenterminal.com/explorer/projects/robinhood/robinhoodchain/metrics?ref=blog.arbitrum.foundation) Robinhood Chain generated more than $800K in revenue in the last 7 days, annualizing to $42M at this rate. [ Check Out the Data ](https://tokenterminal.com/explorer/projects/robinhood/robinhoodchain/metrics?ref=blog.arbitrum.foundation) ### Introducing Swaps by Variational [![var swap.jpeg](https://storage.ghost.io/c/d4/cc/d4cc8040-691e-4dd2-8282-0c08d45fc5a8/content/images/2026/07/var-swap.jpeg)](https://x.com/variational%5Fio/status/2074126508000755983?s=20&ref=blog.arbitrum.foundation) 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](https://x.com/variational%5Fio?ref=blog.arbitrum.foundation) toward bringing TradFi into the programmable economy. [ More Details ](https://x.com/variational%5Fio/status/2074126508000755983?s=20&ref=blog.arbitrum.foundation) ### Rialto Goes Live on Robinhood Chain [![railto.webp](https://storage.ghost.io/c/d4/cc/d4cc8040-691e-4dd2-8282-0c08d45fc5a8/content/images/2026/07/railto.webp)](https://x.com/rialto%5Fxyz/status/2072696289695834345?s=20&ref=blog.arbitrum.foundation) We’re excited to welcome [@rialto\_xyz](https://x.com/rialto%5Fxyz?ref=blog.arbitrum.foundation), an onchain exchange for trading and borrowing against tokenized equities, crypto and real-world assets, launched on the Robinhood Chain. [ Learn More About Railto ](https://x.com/rialto%5Fxyz/status/2072696289695834345?s=20&ref=blog.arbitrum.foundation) ### **Prism is Live on Arbitrum** 0:00 /0:16 1× Arbitrum is building the finance-native platform for the programmable economy. Prism is where the pieces of Arbitrum’s financial stack start coming together. [ Learn More About Prism ](https://x.com/PrismFi%5F/status/2072683758302511510?s=20&ref=blog.arbitrum.foundation) --- ## 🛠️ Dev Tooling & Infra *Updates to SDKs, CLIs, and developer workflows across the stack.* ### ZeroDev Wallet SDK [![5 account flows.jpeg](https://storage.ghost.io/c/d4/cc/d4cc8040-691e-4dd2-8282-0c08d45fc5a8/content/images/2026/07/5-account-flows.jpeg)](https://x.com/zerodev%5Fapp/status/2075481037405110358?s=20&ref=blog.arbitrum.foundation) What does a smart-account-first embedded wallet SDK actually unlock? ZeroDev breaks down [5 product flows to build with the ZeroDev Wallet SDK](https://x.com/zerodev%5Fapp/status/2075481037405110358?s=20&ref=blog.arbitrum.foundation). [ Start Building Today ](https://github.com/zerodevapp/zerodev-wallet-sdk?ref=blog.arbitrum.foundation) --- ## 🗓️ 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. 👇🏻 0:00 /0:58 1× To keep up with upcoming builder programs, funding opportunities, and ecosystem updates, [subscribe to the Builder Newsletter](https://blog.arbitrum.foundation/). --- ## 🧵 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. [ More Details ](https://forum.arbitrum.foundation/t/constitutional-aip-arbos-61-elara/30601?ref=blog.arbitrum.foundation) ### 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. [ Read the Full Factsheet ](https://forum.arbitrum.foundation/t/arbitrumdao-factsheet-robinhood-chain-mainnet-launch/31041?ref=blog.arbitrum.foundation) --- ![](https://storage.ghost.io/c/d4/cc/d4cc8040-691e-4dd2-8282-0c08d45fc5a8/content/images/2026/07/Copy-of-New-Arbitrum-Everywhere-slide-template-1.png) ## Stay Ahead of What’s Next Subscribe to Builder’s Block for more updates, opportunities, and upcoming events from the Arbitrum ecosystem. 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