AI-resolved prediction markets on Arbitrum. Create markets in natural language, settle them with verifiable AI agents, and verify every decision through on-chain proofs and 0G Storage.
OPENCAST is an AI-powered prediction market platform built on Arbitrum that enables anyone to create prediction markets using natural language.
Users can ask questions such as “Will Bitcoin exceed $150,000 by December 31?” or “Will Manchester City win their next match?” and OPENCAST's multi-agent AI system automatically classifies, validates, and prepares the market for deployment.
Every settlement decision is backed by verifiable AI receipts stored on 0G Storage and anchored on-chain through SHA-256 proofs. OpenCast introduces a sovereign verification layer that allows anyone to independently verify market outcomes without trusting OpenCast servers.
Key features include:
• Natural-language market creation
• Multi-agent AI validation pipeline
• Verifiable AI settlement receipts
• 0G Storage integration with on-chain SHA-256 anchoring
• Sovereign verification pages
• Sports, weather, and crypto markets
• Gas-sponsored transactions through Privy
• Arbitrum-native smart contracts
• Per-market thumbnails and rich market discovery
By combining prediction markets, AI agents, decentralized storage, and on-chain verification, OPENCAST creates a transparent and trust-minimized forecasting ecosystem.
<p>During the hackathon, we built OpenCast, an AI-powered prediction market platform on Arbitrum that enables users to create and settle markets using natural language.</p><p>Key achievements during the buildathon include:</p><p>• Built a complete multi-agent AI pipeline for market creation, validation, settlement, and dispute resolution using Mastra and OpenAI<br>• Developed structured AI extractors with confidence-based validation to eliminate incorrect market generation<br>• Designed a locked-parameter architecture that prevents settlement agents from introducing classification inconsistencies<br>• Built support for sports, weather, and crypto prediction markets<br>• Integrated Livescore and Open-Meteo data providers for verifiable market resolution<br>• Implemented verifiable AI receipts stored on 0G Storage and anchored on-chain using SHA-256 proofs<br>• Built sovereign verification pages that allow anyone to independently verify settlement outcomes without relying on OpenCast infrastructure<br>• Developed Arbitrum smart contracts for market creation, outcome tokens, treasury management, and resolver registration<br>• Added gas-sponsored transactions through Privy for a frictionless user experience<br>• Built market image uploads, storage infrastructure, and rich market discovery features<br>• Designed and launched a question-first market creation experience powered by AI<br>• Deployed the full stack to production using Railway, Vercel, PostgreSQL, and Arbitrum Sepolia<br>• Shipped a fully functional MVP with comprehensive automated testing and end-to-end market lifecycle support</p><p>The result is a prediction market platform where markets can be created in natural language, settled by verifiable AI agents, and independently audited through decentralized storage and on-chain proofs.</p>
<p>Bootstrapped.</p><p>OPENCAST is currently being developed through hackathons, community feedback, and ecosystem collaboration. The team is actively exploring grants, strategic partnerships, and ecosystem support opportunities.</p>
