Skip to main content

​
Endpoints

Order Entry Host: margin-mm.fix.elections.kalshi.comMarket Data Host: margin-marketdata.fix.elections.kalshi.com

​
Session Configuration

All connections use FIXT.1.1 with application version FIX50SP2. Only one FIX connection is allowed per API key. Separate API keys are required for concurrent connections.

​
SSL/TLS

You must use TLS 1.2 or higher (not plain TCP) to connect to the margin FIX gateway. Cipher suites follow AWS Network Load Balancer TLS policies. If your FIX implementation does not support native TLS connections, use a local proxy such as stunnel. To obtain the server certificate for pinning on the initiator side:

​
Private Connectivity

For participants requiring network-level isolation, Kalshi supports private connectivity via AWS PrivateLink. With PrivateLink, FIX traffic is routed entirely within the AWS backbone and never traverses the public internet. Members on the Premier tier or above can contact institutional@kalshi.com to provision a PrivateLink endpoint for their AWS account.

​
Rate Limits

  • Limit: FIX application messages use the same token model, token costs, and margin Read/Write buckets as the equivalent REST API operations.
  • Scope: Application messages only (from client to server)
  • Excluded: Logout (35=5), Heartbeat (35=0), TestRequest (35=1)
  • Logon (35=A) is rate-limited.
  • Order-entry messages use the margin Write bucket. See Rate Limits and Tiers for tier budgets and token-cost behavior.
  • Mass Cancel Request (35=q) is limited to 1 request/second.

​
Maintenance Window

See Maintenance and Pauses for scheduled maintenance times and the difference between trading pauses and exchange pauses. Sessions may be disconnected during the maintenance window. Kalshi does not initiate sequence number resets during maintenance; clients should reset sequence numbers on their side when reconnecting. KalshiRT sessions retain message continuity across the maintenance window. If your KalshiRT session is disconnected, you can request retransmission of any messages missed during the downtime after reconnecting.

​
CancelOrderOnPause

To control what happens to your resting orders during a pause, set tag 21006 (CancelOrderOnPause) on your New Order Single (35=D) messages: