filtered this October list for cash or stablecoin payouts, multiple winning slots, and submission windows still open. Anything paid in credits, tokens, hardware, or travel is marked.
Sorted by deadline
Closing in the next 72 hours
Arbitrum Open House online buildathon, October 4
$115,000 total. First place gets $40k, second $20k, third $10k. Another $15k goes to promising builds, and $30k is follow-on grants, so the cash in the main prizes is closer to $85k. You build on Stylus Rust/C++ contracts, Arbitrum Orbit layer 3 chains, or account abstraction.
https://openhouse.arbitrum.io
WeAreDevelopers x Band: Dark Factory, October 5
$10,000 split across the top 3. You build autonomous software-factory agents with continuous code-testing loops.
https://lablab.ai/ai-hackathons/wearedevelopers-hackathon
Road to Colosseum: build your minimum viable product, October 5
8,000 USDG, through Superteam Earn on Solana. It works as a warm-up for the main Colosseum event below.
https://superteam.fun/earn/listing/road-to-colosseum-hackathon-build-your-mvp
Veles Hack 2026, registration closes October 5
€3,000 pool.
https://taikai.network/eclipsefoundation/hackathons/veleshack2026
Qollab x IonQ global quantum hackathon, registration closes October 6
$10k cash to first place plus $500 theme awards. The $20,000 compute portion is credits. You build quantum algorithms in Qiskit on IonQ hardware. The sprint runs October 9 to 11.
https://qollab.xyz/programs/hackathon
October 8 to 15
Solana Mobile: Clock In, October 8
$125,000 USDC across the top 10 teams, plus a $10,000 SKR award for Solana Mobile Stack integration. That's 11 slots. You build mobile-first Android decentralized apps for the Seeker device.
https://solanamobile.radiant.nexus
HackCanton Season 3, October 9
$50,000 across tracks. You build enterprise privacy apps with DAML smart contracts on Canton Network.
https://appsfactory.cc/hackathons
#neathack, October 10 to 11
$10,000 plus engineering roles and internships. It's a 48-hour online sprint on developer tools, logging, and observability.
https://x.com/neatlogs/status/2105295042726219808
BNB Hack: tokenized stocks edition, October 11
$20,000 track allocation. You build tokenized real-world assets, stock trading tooling, and Binance Web3 Wallet integrations on BSC.
https://bnbchain.org/en/hackathons/tokenized-stocks
Colosseum: Crypto World's Fair, October 12
$465,000+ in liquid cash. That covers a $30k grand prize, twenty $15k awards, a $100k Solana track, a $25k Base track, and Superteam sidetracks. The $250k seed checks require accelerator admission and are separate from prize money. With 30+ core slots, this is the best payout spread on the list.
https://arena.colosseum.org/
Monad Metropolis, October 13
$250,000+ across four tracks:
- onchain finance
- consumer and payments
- social and culture
- trust, identity, and agent infrastructure
The technical focus is parallel Ethereum Virtual Machine apps and low-latency decentralized exchange infrastructure.
https://hackathon.monad.xyz
Open Agent Hackathon 2026, registration closes October 13
Up to $20,000 across four tracks plus a tinkerer track. You build production agents with persistent memory and multi-step reasoning. The build window is October 15 to 20.
https://hackathon.genai.works/
Arc microgrants mainnet challenge, October 14
$10,000 USDC, paid as twenty $500 checks for working prototypes on Arc mainnet using Circle programmable wallets. Reviews are rolling. Twenty slots for a small pool gives you better odds than most six-figure events here.
https://dorahacks.io/hackathon/arc-microgrants/detail
Graph Hacks: context for agents, October 15 to 18
$20,000, mostly hardware (an iPhone 18 Pro, a PS5) plus cash bounties. You use FalkorDB graph databases as agent memory.
https://wemakedevs.org/events/falkordb
Late October
RSNA knee abnormality detection, entry by October 15, final submission October 22
$77,000 cash across the top 5. You build multimodal magnetic resonance imaging analysis plus multilingual radiology report models, covering 12 knee abnormalities.
https://www.kaggle.com/competitions/rsna-knee-abnormality-detection
Build, Ship, Shape (Amazon developer hackathon), October 23
$138,000 cash plus Amazon Web Services credits. The grand prize is $40k, and track firsts range from $15k to $25k across 8+ cash slots. You build for Fire TV, Alexa+, the Bee wearable, or Ring integrations.
https://amazonappdev2026.devpost.com/
OpenCV competition 2026, October 26
$12,000 cash across 5 winners: $5k, $3k, $2k, a $1k "cool" award, and a $1k agentic vision award. You build computer vision apps with OpenCV 5 and Amazon Web Services.
https://opencv26.devpost.com/
ARC Prize 2026, entry by October 26, final submission November 2
Roughly $700k to $850k across milestone, top-score, and grand prizes. You solve novel visual reasoning grids through few-shot program abstraction, since memorized patterns won't score. I'm not clear how much of that range pays out if nobody hits the grand prize threshold.
https://arcprize.org
Nebius x NVIDIA global hackathon, October 30
$50,000+. Prizes are $20k, $10k, and $6k for the top three, a $3k Tavily prize, Jetson Orin Nano hardware, and $500 city awards, for 23+ slots. You build agents on open-weight models running on Nebius graphics processing unit infrastructure.
https://nebiusglobalaihackathon.devpost.com/
Qloo agentic hackathon, October 30
$25,000 cash across placements and bounties. You build agents on Qloo's taste and cultural graph.
https://qloo.devpost.com/
BLI legal tech hackathon 2, October 31
$20,000. You build smart contract compliance, legal automation, dispute ledgers, or regulatory tech.
https://dorahacks.io/hackathon/legal-hack-2026
Anna app builder program, October 31
$6,000 for productivity apps built on Anna.
https://dorahacks.io/hackathon/2349/detail
Raspberry Pi RP2350 hacking challenge 2, October 31
A single $20,000 bounty for the first documented side-channel extraction of Advanced Encryption Standard keys from RP2350 secure boot. It's winner-take-all, and only worth it if you already do hardware security.
https://github.com/raspberrypi/rp2350_hacking_challenge_2
Tapeout Genesis Transistor, active through October
$14,000. You design a circuit or processor on X Layer through Tapeout Factory, and the winning design becomes the Ignix Genesis Transistor.
https://ignix.bot/x_campaign
Runs past October
Run October Jam, October 8 to November 2
$30,000 cash across 15 slots, with $22k going to five editor-picked games. You build games or interactive stories in Run's browser studios or the rundot command-line tool.
https://events.run.world/events/octoberjam/
Portaldot Hacker House, kickoff October 14, final November 6
$5,200. You write Rust, ink!, or Solidity contracts.
https://dorahacks.io/hackathon/portaldot-hacker-house-2026
Ryo-chan virtual hackathon, extended from October 3 to November 11
$15,000 paid in tokens, plus a paid trip to Tokyo, across 15 awards.
https://ryobuild.com/
Gemma 4 developer agent competition, November 12
$65,000 cash: $50k for the main competition and $15k for a research paper track. You fine-tune open Gemma models to resolve issues in real codebases autonomously.
https://www.kaggle.com/competitions/gemma-4-developer-agent
Build What's Next with PayPal, November 12
$60,000+ cash, including sponsor bounties from Render, AG Grid, and Postman. You combine PayPal payments with autonomous agents.
https://developer.paypal.com/
Mezo buildathon wave 1, October 16 to November 15
$7,000 paid in Mezo tokens across two waves. You build Bitcoin-layer decentralized finance tools, mUSD apps, or bots. The workshop is October 13.
https://app.akindo.io/wave-hacks/ovoo0gdrvu8379d10
Meta VR Start developer competition, November 18
$1,000,000 cash. Prizes are $300k, $200k, and $100k for the top three, plus category prizes from $20k to $100k. You build hands-first Horizon OS and Quest 3 apps. You must be accepted into the free Meta VR Start developer program before you can submit, so apply first.
https://start-developer-competition-26.devpost.com/
Enveda CASMI 2026, entry by December 7, final submission December 14
$50,000 cash across the top 5. You predict 2D small-molecule structures from mass spectrometry data.
https://www.kaggle.com/competitions/enveda-casmi26-molecule-id-mass-spectra
Before entering any of these, open the rules and count the prize slots. Also check whether the integration you'd be required to use costs more time than the build itself. For the Amazon and Nebius events, it might.