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Documentation Index

Fetch the complete documentation index at: https://docs.kalshi.com/llms.txt

Use this file to discover all available pages before exploring further.

Overview

A listener session provides a real-time, read-only stream of execution reports from your margin trading session. This is what most exchanges refer to as a “drop copy”: a live shadow feed of all fills and order state changes. Kalshi’s Drop Copy session (KalshiDC) is a separate request-response tool for querying historical execution reports, not a live feed.

How It Works

A listener session is not a separate endpoint. It is a mode enabled on a standard KalshiNR or KalshiRT order entry session by setting ListenerSession=Y (tag 20126) during Logon. Once connected, the listener session receives the same execution reports as your active trading session in real time, but cannot send any orders or modifications. Listener sessions connect to the same KalshiNR or KalshiRT endpoints listed on the Connectivity page. A separate API key is required (read-only scope is sufficient).

Logon Configuration

Required Logon Fields

TagNameValueDescription
20126ListenerSessionYEnables listen-only mode
21011SkipPendingExecReportsYRequired when ListenerSession=Y

Restrictions

The following Logon flags are not compatible with listener sessions:
TagNameRestriction
8013CancelOrdersOnDisconnectMust be N (or omitted)

What You Receive

Listener sessions receive ExecutionReport (35=8) messages for all order activity on your account, including:
  • New order acknowledgements
  • Fills and partial fills
  • Order cancellations
  • Order replacements

What You Cannot Do

Listener sessions are strictly read-only. The following message types will be rejected:
  • NewOrderSingle (35=D)
  • OrderCancelRequest (35=F)
  • OrderCancelReplaceRequest (35=G)
  • OrderMassCancelRequest (35=q)