33 Hackathons in September 2026: Ranked by Prize Quality, Deadline, and What You Actually Win

Developer Emma (@_HEISEMMA) went through every hackathon open this September and ranked 33 of them S, A, B, or C — not by banner prize number, but by whether the payout is actually cash. Credits, tokens, and hardware are not the same thing. That distinction cuts the real prize pool on several high-profile competitions by 80% or more.

Some deadlines on this list hit on 3 September. If you are still deciding whether to enter, that window is already closing.

S-Tier: Build Around These

S-tier picks are worth reorganising your schedule for. The prize pools are real cash, the submission windows give you time to build something solid, and the requirements are specific enough that the competition is meaningful.

ETHOnline 2026 — $100,000

Twelve async days from 4 September, submission deadline 16 September. Sponsors include Hedera, The Graph, Uniswap, Ledger, 1inch, and World. Registration is open. The prize pool is $100,000 across sponsor tracks — the standard ETHGlobal structure, where picking two or three overlapping sponsor tracks from a single build is the right move. ethglobal.com/events/ethonline2026

RevenueCat Shipaton 2026 — $740,000+

The grand prize is $100,000. Category firsts run $10,000–$20,000. The requirement is a new iOS, Android, or macOS app with the RevenueCat SDK, first published between 1 August and 30 September. Submission closes 30 September. If you have already been building a mobile app this summer, check whether your publish date qualifies — this one may already be winnable. devpost.com/revenuecat-shipaton-2026 (full Shipaton breakdown here)

Monad Metropolis — $250,000

Registration closed 1 September; submission runs to 13 October. $30,000 per track across four tracks, plus a $25,000 grand champion prize. Winners announced 3 November. Existing repos qualify if the new work falls within the competition window. monad.xyz

Arbitrum Open House Singapore — $115,000

Online buildathon, registration closes 2 October, submission 4 October. First place $40,000 USDC, second $20,000 USDC, third $10,000 USDC, plus $15,000 for promising products and $30,000 in grants. Existing products are allowed. arbitrum-singapore.hackquest.io

Agentic Cinema — $75,000

Five tracks, each paying $7,500 first, $4,500 second, $3,000 third. Submission closes 9 September at 21:00 UTC. Registration is open now. devpost.com/agentic-cinema

Commons Made — $60,000

First place $20,000, second $8,000, third $4,000, places 4–19 each $500. Submission deadline 17 September. Registration opened 27 August. One build per team. commonsmade.com/hackathons

Emma Hackathon — $50,000

Application-gated. Submit by 20 September; payout within 14 days of 26 September. First place $25,000, second $15,000, third $7,000, people’s choice $3,000. Teams of 1–5. Apply now — compute credits come after approval, not before. hackathon.emma.ms

Build the Era (BNB Agent Studio) — $40,000+ in sponsors

Submission closes 9 September. $30,000 USDT from BNB plus $10,000 from Termix and additional sponsor prizes from PancakeSwap, Altana, and AltLayer. The requirement is a marketplace, not a single agent. bnbchain.org

Agents for Humans (AWS Strands) — $40,000

Requires the Strands SDK. Submission 14 September (or 15 September 00:00 UTC). Registration is open. Read the required integration before writing a line of UI. devpost.com/agentsforhumans

Convex All Gas — $16,500

First $10,000, second $5,000, third $1,500. Submission 22 September 19:00 UTC. Requires Convex backend. New apps only — created after 25 August. Teams of 1–4. On Luma, not Devpost. Check your repo creation date before entering. luma.com/convex-allgas-hackathon

BUIDL CTC 2026 Fall — $15,000

Submission 13 September. Requires integrating Attestcoin and deploying on testnet. First $10,000, second $3,000, third $2,000. Winners announced 20 September. dorahacks.io

A-Tier: Strong If You Have Something Ready

A-tier competitions are worth entering, but most reward builders who are already mid-build rather than starting from zero on 3 September.

• OKX Dev Day 2026 — Up to $100,000 across teams. Online build 17–25 September, finale in Singapore 6 October. Travel is unpaid. Apply by 11 September. luma.com
• ARC Prize 2026, ARC-AGI-3 Milestone 2 — $37,500 milestone cash. Kaggle competition. Submission 30 September. No internet during eval; no GPT or Claude APIs. Pure research. arcprize.org
• WebMCP (OpenAI) — $35,000. Top 10 each get $3,000 cash. Deadline: 3 September. For demos that already exist. devpost.com/webmcp
• Open Agent Hackathon 2026 — $20,000. Grand $8,000, second $4,000, third $2,000. Registration closes 5 October, submission 9 October. genai.works
• DevNetwork [API + Cloud + AI] 2026 — $19,000 plus credits. Hybrid — online build with optional in-person awards in Santa Clara. Submission 3 September. devpost.com
• Nebius x Nvidia — $50,000. Grand $20,000. Registration and submission both close 30 October. Requires Nebius compute and at least one Nvidia OSS model. Note: Jetson Orin Nano is hardware, not cash. devpost.com
• Kaggriculture — $50,000. Top 10 places, $5,000 each. ML contest, not a product hack. Submission 30 September. kaggle.com
• Victoria VR AI Builder Hackathon 2026 — €20,000. Browser-native 3D. Registration closes 8 September; submission 11 November. First 10 registrations get up to €400 in AI credits. victoriavr.com
• IBM BOB 2.0 — $10,000. 48-hour sprint. Registration closes 25 September; submission 27 September. lablab.ai
• Call-E: Your Code Is Calling — $10,000. Most practical $4,000, most innovative $3,000. Submission 14 September 15:45 UTC. Requires a PR and demo. devpost.com/call-e
• KeeperHub — $5,000. Requires a real KeeperHub transaction, demo, and repo. Submission 18 September. OFAC countries excluded. dorahacks.io
• AssemblyAI Voice Agents — $5,000 cash plus $5,000 in credits. Register any time in September; submit by 30 September. lablab.ai
• Celo Agents at Work — $5,000. Prizes paid in $CELO, not USD. Submission 14 September. Tag transactions from day one using the npx skills command. celobuilders.xyz
• Base Builder Quests — $5,000 pool. Build something that helps people trade or use Coinbase tokenised stocks on Base. No close date published yet. x.com/buildonbase
• Telegraph Season I, Round 1 — $5,000 this round, $15,000 season total. Submission 7 September. Round 2 in October is $10,000. telegraphprotocol.com
• Alpaca AI Trading Agents — $6,000. First $2,500, second $1,500, third $1,000. Submission 4 September 16:00 WAT. US withholding may apply. lablab.ai

B and C-Tier: Enter Only If You’re Already Ready

B-tier competitions have smaller pools or token payouts that aren’t straight cash. C-tier is students-only or payout so small the time investment doesn’t stack up unless you are already sitting on a working demo.

• BuildArena S01 (B) — $3,000 on Kaggle. Requires Besiege plus Broken Beyond DLC. Submission 12 September. kaggle.com
• Veles Hack 2026 (B) — €3,000. Valencia plus online hybrid. Registration closes 5 October, submission 8 October. taikai.network
• Event Contracts (Somnia x DreamDex) (B) — $5,000 USDSO. Token, not USD, until it hits your wallet. Submission 8 September. dorahacks.io
• Speed September AI Challenge (C) — $1,500. Students only. Submission 20 September. devpost.com
• 3rd-Web-Hack (C) — $750. Students only. Submission 27 September. devpost.com
• GatewayHacks 2026 (C) — Banner says $591,585. Actual cash is $50 first place. Students only. Submission 2 October. devpost.com

Nine Rules That Separate Winners From Participants

Emma’s practical notes from the thread are worth keeping open in a second tab while you plan:

Read the required integration first. Attestcoin, Strands SDK, Convex backend, RevenueCat SDK, KeeperHub transaction, Celo attribution tag. If that piece is missing, you are building for fun. Don’t write a line of UI before confirming the core requirement is achievable.

Crowded competitions are demo contests. Judges will not read your repo. Two minutes, one screen that proves the thing works, one number. The write-up matters less than most builders assume.

One repo, two or three bounties. ETHOnline is not a grand prize hunt. Pick sponsor tracks that the same build can hit simultaneously.

Check the new-app window. Convex requires apps created after 25 August. Shipaton requires first published between 1 August and 30 September. An old GitHub creation date can disqualify you after you have already built.

Apply to gated ones first. Emma Hackathon is application-gated. Compute credits come after approval. You cannot start building on day 20 of a 20-day window.

Don’t start from zero on 3 September. WebMCP and DevNetwork are for demos that already exist. If you need a new idea, find an S-tier with a later submission date and give yourself the runway.

Submit four hours early. A failed upload at 23:59 UTC is a DNF. The last 24 hours should be video, write-up, and required checklist — not a rewrite of the product.

Treat unpaid travel as hybrid. OKX Dev Day is not an online-only hackathon if you make the Singapore finale and flights are on you.

Record the demo before the last feature. The final 24 hours should not be a product rewrite. Get the demo done first.

The full ranked thread is on X from @_HEISEMMA. For context on how competitive the developer hackathon space has become this year, OpenAI Build Week drew 40,000 developers to a single $100K competition in July — and builders are finding creative formats beyond standard online submissions.

Frequently Asked Questions

Which September 2026 hackathon has the biggest cash prize?

ETHOnline 2026 offers $100,000 in cash across sponsor tracks, with a submission deadline of 16 September. The RevenueCat Shipaton banner reads $740,000+ but the actual grand prize is $100,000 cash — the rest is split across category prizes and credits.

Are the prize numbers on hackathon banners accurate?

Often not. GatewayHacks 2026 advertises $591,585 — the actual cash first prize is $50. Credits, tokens, hardware, and cloud compute are not cash. Check the prize breakdown before entering, not the banner headline.

Which hackathons close first in September 2026?

WebMCP (OpenAI) and DevNetwork both close 3 September. Alpaca AI Trading Agents closes 4 September. These are for builders with something already working — not a starting point for new projects.

Can I enter multiple hackathons with the same build?

Yes, in many cases. ETHOnline explicitly supports entering multiple sponsor tracks with one project. Check each competition’s rules on simultaneous submissions — some prohibit it, but most online hackathons permit it as long as the project was started within the competition window.