The Encode x Arc DeFi Hackathon is a builder event run by Encode Club and Circle where you ship real DeFi on Arc, Circle's stablecoin-native Layer 1 blockchain that uses USDC as its gas token. It exists to seed the first wave of developers building lending, swaps, FX, yield, and payments on Arc, with mentorship from Circle and a direct path into the Circle ecosystem for the teams that ship.
If you want the short version: it is a focused, DeFi-first hackathon on a brand-new chain, backed by one of the most credible stablecoin companies in the world, and it is one of the cleanest ways to become an early, verifiable Arc developer before the mainnet crowd shows up.
Who runs it and what Arc actually is
Two names matter here. Encode Club is a long-running Web3 education and hackathon organizer that runs programmes with major protocols and operates Encode Hub in London. Arc is the chain, built by Circle, the company behind USDC.
Arc is a Layer 1 blockchain purpose-built for stablecoin finance. Three facts define it and you should know them cold before you build:
- USDC is the gas token, so fees are low, predictable, and denominated in dollars instead of a volatile native coin.
- Settlement is sub-second, using a consensus engine called Malachite from Informal Systems, which Circle absorbed.
- It is EVM-compatible, so your Solidity, Foundry, Hardhat, and existing tooling carry over.
Arc ships with Circle's full developer platform wired in: USDC and EURC, CCTP for cross-chain transfers, Circle Wallets, Contracts, Paymaster, and Circle Mint. Per Circle's own timeline, Arc moved through private and public testnet in late 2025 with mainnet beta slated for 2026. That timing is exactly why a hackathon right now is valuable. You are building while the chain is still young.
Dates and format
Be careful here, because there is more than one Arc hackathon and the details differ. The in-person Encode x Arc DeFi Hackathon runs at Encode Hub, 41 Pitfield St, London N1 6DA. It is a 3-day, twice-overnight format for roughly 300 builders: Friday check-in and launch, a full 24 hours of hacking Saturday, then submissions and a pitch finale midday Sunday.
Encode and Circle have also run online "Programmable Money" editions, described as roughly 4-week online hackathons where top teams earn places in a multi-week accelerator. Encode has publicly confirmed the DeFi Hackathon returned for a second edition, and some listings reference late-February dates for a follow-up.
I am not going to hand you a single locked date, because the editions overlap and dates shift. Check the official Encode Club programme page and the event's Luma listing for the exact dates of the round you are entering, and confirm whether it is in-person London or online before you plan travel or team logistics.
Tracks and prizes
The core theme is DeFi on Arc. Across editions, the tracks have centered on:
- DeFi primitives: stablecoin-native lending, borrowing, swaps, liquidity, FX, and yield.
- Payments, treasury, and fintech infrastructure: real-world money movement using USDC as gas and settlement.
- Agentic economy: autonomous AI agents that hold wallets and pay, settle, and transact in USDC without a human in the loop.
On prizes, one publicly listed figure for the in-person London DeFi edition is a $10k prize pool. Treat that number as edition-specific and verify it for your event, because prize pools and the exact split across winners are not consistent across every Encode x Arc run. The bigger prize is usually structural: mentorship from Circle engineers during the build, and for standout teams, an accelerator place and a path into the Circle ecosystem. For most builders, that relationship is worth more than the cash line.
How to actually win
Judges at a chain-specific hackathon reward one thing above all: something that could only exist, or works meaningfully better, because of Arc. Aim there.
Use the Arc-native features on purpose. Do not port a generic Ethereum DeFi app and swap the RPC. Build something that leans on USDC-as-gas and sub-second settlement: gasless-feeling UX where users never hold a separate gas token, high-frequency settlement flows, agentic payments, or treasury tooling where dollar-denominated fees are the whole point. If your demo would be identical on any EVM chain, you have already lost the Arc angle.
Ship a working demo, not a deck. A live transaction on Arc testnet beats a beautiful pitch every time. Have a real contract deployed, a real USDC flow, and a URL a judge can click. Twice-overnight formats punish teams that spend Saturday designing and Sunday panicking.
Scope brutally. One tight flow that works end to end wins over five half-built features. Pick a single user, a single job, and finish it.
Talk to the mentors early. Circle engineers are in the room or the Discord. Ask them what is hard on Arc, what CCTP or Paymaster can do, and what they wish someone would build. That is free signal on what judges care about.
Nail the 2-minute pitch. Problem, what you built, live demo, why Arc. Rehearse it. A crisp finale pitch on a real build is how borderline projects get remembered.
Why building here positions you for future airdrops
Ecosystems reward developers they can see. When you build for the Encode x Arc DeFi Hackathon, you generate exactly the signals that early-ecosystem teams look for later: a deployed contract with an on-chain history on Arc, a public repo, a project other builders can point to, and a relationship with Circle's team formed during the event.
Arc is new, backed by Circle, and heading toward mainnet. Being a genuine, early, verifiable Arc developer, not a wallet farming testnet clicks, is the profile that stands out when an ecosystem decides who its real contributors are. Airdrops, when they happen, tend to favor demonstrable builders over anonymous addresses. A hackathon submission is one of the strongest public proofs of that you can produce.
To be blunt about the honest part: none of this guarantees anything. Airdrops are never guaranteed, and no one, including DEPLOYR, can promise you a payout. What you can control is becoming the kind of developer that ecosystems and their future rewards actually look for.
Ship it, and make it count
That is where DEPLOYR comes in. We help you turn hackathon builds into a real onchain developer identity: a live storefront of what you have shipped, so your Arc project is not buried in a Devpost graveyard but front and center where ecosystems, recruiters, and grant committees can find it. Explore /build to structure your build, browse /hackathons for events worth your weekend, and read /insights for how early builders position themselves.
Go build something on Arc that could only work on Arc. Then make sure the right people can see it. And remember the permanent honesty line: airdrops are never guaranteed. Being a real builder is the only edge that is actually yours to keep.