Prediction Market Platform

Overview

• —REST API built with Elysia on Bun runtime — typed route definitions with schema validation at the handler level
• —Real-time odds updates via polling with SSE fallback; probability recalculated server-side on every bet
• —Market lifecycle management: creation, active betting, resolution, and automated payout distribution
• —Leaderboard with ranking derived from resolved market outcomes and cumulative profit/loss
• —API key authentication for programmatic market access alongside session-based browser auth

Screenshots

Authentication entry point. Session tokens are issued by the Elysia API and stored client-side; the React frontend redirects unauthenticated requests to this view.

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Architecture

• —Backend: Elysia framework running on Bun — typed route handlers with built-in schema validation using Elysia's type system
• —Frontend: React with TypeScript, custom hooks for market state and polling-based live odds synchronisation
• —Persistence: SQLite via Bun's native SQLite bindings — single-file database appropriate for the current scale
• —Real-time: HTTP polling on the frontend; server-sent events as a lower-overhead alternative for odds streams
• —Auth: session tokens for browser clients, API keys for programmatic access — both validated in Elysia middleware
• —Probability model: simple constant-product market maker — recalculated on each bet, stored as a float in the market record

Engineering Challenges

• —Maintaining odds consistency under concurrent bets: SQLite write locks serialize conflicting transactions; at higher scale this would require a proper queue or optimistic locking strategy
• —Keeping the React frontend in sync with server state using polling: debounced interval fetches balance responsiveness against API load
• —Automated payout calculation on resolution: settlement runs as a single SQLite transaction to ensure all winners are credited atomically or not at all
• —Typed API contracts between Elysia and the React client without a code-generation step: shared TypeScript types in a common module ensure the frontend and backend agree on shape

What I'd improve

• —Replace polling with persistent WebSocket connections for lower-latency odds updates
• —Improve test coverage across API route handlers and probability calculation logic
• —Extract shared UI components into a dedicated internal package
• —Add market resolution dispute flow for contested outcomes