People come to prediction markets to make money from better forecasts, but being right is only the beginning. Thin liquidity, fees, slippage, bad sizing, and software mistakes can erase an apparent edge. PredArena gives manual traders, bots, and AI agents a place to test trades against live market conditions before those mistakes cost real money.

PredArena is a live-orderbook trading and trade-analytics platform for Kalshi and Polymarket. Use the dashboard as a manual trader, or route orders through the API as a bot builder. Either way, orders walk live production books, apply venue fee models, and record fills, positions, P&L, and execution quality.

How it works

1. Create a portfolio with a starting balance.
2. Browse live Kalshi and Polymarket markets in the dashboard, or generate an API key for a bot.
3. Place market, limit, stop-loss, take-profit, or bracket orders against live venue depth.
4. PredArena walks the live order book depth level by level, simulating realistic VWAP fills, slippage, fee drag, and balance impact.
5. Track open positions, realized P&L, CSV exports, and shareable public trading records.

Current product scope

PredArena supports live Kalshi and Polymarket market data, market and limit orders, stop-loss, take-profit, bracket orders, cancellation, portfolio analytics, watchlists, price alerts, API keys, webhooks, and CSV export. It does not route real orders or provide historical replay/backtesting; it simulates forward against live data.

Core mechanics

Volume-weighted average price slippage

Traditional simulators naively fill orders at the mid-market price. PredArena does not. When you or your bot submits a trade, the fill engine walks the live bid/ask book. If your order exceeds the volume at the best quote, it walks deeper into the book and records the volume-weighted average price. Orders exceeding available displayed depth are rejected instead of pretending they filled.

YES/NO order-book normalization

Prediction markets have linked YES and NO books. PredArena normalizes venue order books into the prices you can actually buy or sell, so fills reflect the available liquidity for the side you are trading.

What you get

A clean trading environment for learning, journaling, strategy testing, and public proof. Run multiple portfolios, compare manual ideas against bots, inspect fee-aware P&L, and share records without exposing your real venue account.