KALSHI API Documentation: How to Access KALSHI Data for Arb
Kalshi provides an API surface for programmatic access to markets, events, series, and trades. This article outlines the kalshi api documentation at a high level and explains how a trader can use the REST and WebSocket feeds to monitor markets, build arbitrage alerts, and integrate with KalshiKlear for settlement. We’ll focus on the practical, edge-driven patterns that matter for intra-market and combinatorial arbitrage, while keeping in mind Kalshi’s USD settlement and regulatory framework. If you’re evaluating automation, this guide helps you align your tooling with Kalshi’s data and execution surface.
Overview of Kalshi APIs and what you can build
Kalshi exposes a REST API and a WebSocket feed. Read-only endpoints let you fetch markets, markets detail, events, and series, while authenticated endpoints handle portfolio orders, positions, and fills. The platform uses a USD settlement model and a centralized clearinghouse, so any automated strategy must respect Kalshi’s resolution rules and per-contract pricing. The API surface is designed for real-time data streaming and deterministic trading actions with proper API key authentication and signed timestamps. In practice, you’ll use the REST endpoints to snapshot market state and the WebSocket stream to keep a low-latency view of the order book and trades.
Read-only data you’ll typically pull
The read-only endpoints provide markets, a single market, order book snapshots, and historical candlesticks. You can also list events and series to understand the hierarchical structure of MUTUALLY EXCLUSIVE markets under a shared event ticker. Pricing is shown on a per-contract basis in cents, and contracts are binary YES/NO with a 1.00 settlement value. This data is essential for identifying edge conditions like when bestAsk YES plus bestAsk NO dips below 1.00, or when a cluster of child markets under one event shows a favorable spread for a complete set.
Authenticated trading endpoints and practice safety
For trading actions you’ll use authenticated endpoints that require an API key and an ECDSA-signed timestamp. These endpoints let you place, cancel, and manage orders, as well as fetch your positions and fills. Kalshi enforces self-trade prevention and typical market protections; you’ll want to implement robust error handling around order submission, fee calculation, and potential slippage. Always test in a sandbox or with small stakes before scaling, and be mindful of per-contract fees that apply to both makers and takers.
Arb patterns you can enable with the API data
Intra-market binary arbitrage relies on pricing inefficiencies where bestAsk YES and bestAsk NO sums fall short of $1.00. The API data makes it feasible to identify these gaps and script alerting or auto-bidding when conditions are favorable. Combinatorial arbitrage across event children is another pattern: if the sum of child YES asks is below $1.00, you can target a complete set of child YES contracts. The final hours before settlement offer edge opportunities as well, but you must account for resolution rules and potential liquidity constraints. KalshiArb helps by converting data into actionable alerts and autonomous execution logic.
Join KalshiArb for Kalshi API-driven edge
Get access to alerting and execution tooling designed for Kalshi API data. Our pricing covers alerts or autonomous AI agents that work with your Kalshi API key to target sub-100ms reaction times and YES/NO < $1.00 opportunities.
FAQ
- What is kalshi api documentation typically used for?
- Traders use the Kalshi API docs to understand how to pull market data, subscribe to real-time feeds, and place trades programmatically. The focus is on read-only data for market monitoring and authenticated calls for order management.
- Are there limitations with the API I should know?
- Yes. You should refer to Kalshi’s live rulebook for limits on endpoints, rate limits, and per-contract fees. The FAQs and API docs typically outline authentication requirements and the separation between read-only and trading endpoints.
- Can I automate YES/NO arbitrage using the API?
- Automating YES/NO arbitrage is possible by combining live orderbook data with resolution rules and fee models. You’ll need authenticated trading endpoints, proper timing, and risk controls to avoid slippage and disputes at settlement.
- How does settlement affect API-based strategies?
- Settlement proceeds to $1.00 on the winning side and $0.00 on the losing side, based on Kalshi’s resolution rules. Your API-driven strategy must handle order fills, fees, and potential late settlements or outages.