Kalshi Trade API v2 — Vendor Facts

Pinned from docs.kalshi.com on 2026-09-04. Do NOT re-fetch from the network (GUARDRAILS.md §1.4).

Base URLs

• Production: https://external-api.kalshi.com/trade-api/v2 (alt: https://api.elections.kalshi.com/trade-api/v2)
• Demo: https://external-api.demo.kalshi.co/trade-api/v2
• WebSocket (NOT used in this kit): wss://external-api-ws.kalshi.com/trade-api/ws/v2

Authentication

Signature-based with RSA private key:

• Headers: KALSHI-ACCESS-KEY (public key ID), KALSHI-ACCESS-TIMESTAMP (ms), KALSHI-ACCESS-SIGNATURE
• Signature algorithm: RSA-PSS(SHA256, MGF1-SHA256, salt length = digest length)
• Signed string: f"{timestamp_ms}{METHOD}{path}" where path is URL path WITHOUT query string
• Example: sign /trade-api/v2/portfolio/orders, not …?status=open
• Private key format: PEM-encoded