Builder's Block #025: Arbitrum's Buildathon Starts Next Week, Here's How to Stand Out in Open House

📣 Announcements

Key updates from the Arbitrum ecosystem and Foundation.

Arbitrum's Online Buildathon - Open House Singapore - Brings $415k In Prizes + Grants to Early Stage Teams

Here’s how you can win:

The 1st phase of Open House Singapore kicks off with a 3-week online Buildathon next week on September 14th.

Here Jess breaks down:

• What you can win
• The types of projects we’re looking for
• Why builders should join

Arbitrum Foundation Reports First Half 2026 Progress Update

Over the first six months of 2026, the Arbitrum Platform has ramped up its efforts in driving long-term growth and sustainable value back to the ecosystem. This includes:

• Bringing Robinhood Chain out of stealth and expanding the Arbitrum Platform with LG, Mastercard, Cash App, Venmo, Ramp, PayPal & more
• Generating $6.19M in H1 income across 4 revenue lines (with more to come)
• Doubling down on support for early-stage teams with Open House & Mentorship Program

📚 Learn & Build

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

Keynote Preview from Offchain: To Be Or Not To Be Onchain

Building a great onchain product starts with two questions:

• Does it need to be onchain?
• If so, what unique problem does it solve?

Hear @zkLumi, from Offchain, give advice to builders at Open House on how teams can answer both and ship with purpose.

Why We Need MEV & How to Strike the Balance

Maximal Extractable Value (MEV) is the extra profit that block creators can extract by choosing which transactions to include, exclude, or reorder within a block. This article by @0xjesstech breaks down the impact of MEV, and how chains, protocols, and users are managing the impacts.

Fireside Chat: Security Foundations with OpenZeppelin

Building the biggest onchain products starts with security.

Learn how building a strong security foundation from day one can protect users and help your product scale with @PepeBlasco_tech from OpenZeppelin.

Fireside Preview: User Onboarding with ZeroDev

The most widely used consumer apps have the best wallet infrastructure.

Learn from Kensie England on how you can simplify user onboarding with ZeroDev.

Tips for Founders Joining the Upcoming Arbitrum Open House Buildathon

• Double down on the foundation before adding more features
• Keep your infrastructure simple so you can ship faster

Hear more from @PepeBlasco_tech at OpenZeppelin.

Founder Testimonial - Nathan Vandy, Cofounder & CEO, Bond Credit

Nathan from Bond.Credit shares how they reached $12M in volume and $100K+ in assets under agent with the right support from Arbitrum's Open House NYC and London builder programs.

If you’re a hungry team looking to bring an idea or MVP out of stealth, apply to our online Buildathon beginning September 14th.

🔦 Ecosystem Highlights

Fresh launches and standout threads from around the Arbitrum ecosystem.

Spend Market: Pioneers of the Programmable Economy for Consumers

Spend Market (by @americanspend) is turning U.S consumer spending habits into programmable markets anyone can trade on - pioneering a new category based on real spending habits across food, tech, and finance powered by Arbitrum's speed and deep liquidity.

RWAs on Arbitrum Reached $1B

RWAs on the Arbitrum Platform (Arbitrum One + Robinhood Chain) soar to $1B in market cap.  The future of finance is programmable. 

Swaps Are Live: TradFi Liquidity Is Now On-Chain

TradFi markets just got a lot more programmable on Arbitrum. Starting with gold (XAU) and Nasdaq-100 (US100), Variational’s first swap markets bring TradFi liquidity onchain.

🛠️ Dev Tooling & Infra

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

Arbitrum Nova Minimization: Migration Window Concluded

The 90-day migration window in which developers and users were encouraged to migrate from Arbitrum Nova to Arbitrum One has concluded. From today, Arbitrum Nova will be transitioned into a minimized state, with Nova-specific developer and user support deprioritized.

Note: Developers and users will still be able to migrate from Arbitrum Nova to Arbitrum One, albeit with less support and potentially fewer bridging solutions available.

🗓️ Events

Workshops, hackathons, and ecosystem meetups to watch.

Open House Singapore online Buildathon Kicks Off September 14

Open House Singapore will kick off with a 3-week, online Buildathon on September 14, designed to help founders refine their direction and iterate towards an MVP. Teams that are looking to bring novel financial products to the Arbitrum Platform are welcome to apply today.

Founder House Singapore is Coming to Singapore on October 23

Following the online Buildathon, Founder House Singapore is an application-only, three-day, in-person experience built for founders and teams who already have an existing product, prototype, or business and are actively building.

​Selected teams will spend three focused days alongside fellow founders, ecosystem leaders, and mentors, working to ship meaningful product progress, validate key assumptions, and receive direct feedback from the Arbitrum ecosystem.

🧵 Forum & Community Discussions

What builders are debating and proposing this week.

OpCo Update August 2026

Find the general updates from OpCo that cover everything we and the OAT have been working on throughout August. Going forward, monthly OpCo updates will be posted from this account, as opposed to having an OAT member publish them.

[RFC] Operational Mandate: Arbitrum Stylus Developer Impact Oracle & Sybil-Resistant ROI Matrix

As current Domain Allocator and incentive programs approach their conclusion, the Arbitrum DAO faces a critical vulnerability: they are spending millions of dollars on developer grants without a programmatic way to track post-grant retention.

This proposal introduces the Stylus Developer Impact Oracle, a custom Dune Analytics and SQL tracking architecture designed to audit the historical ROI of concluding programs and provide a verifiable data baseline for all future Arbitrum DAO allocations.

That’s all from Builder’s Block #025. Thank you for reading, and keep building. Arbitrum Everywhere.