The Perps API is how you trade Kalshi’s perpetual futures. “Perps”, “margin”, and “perpetual futures” all refer to the same product. The API surface uses margin throughout (endpoints under the /margin namespace, margin-prefixed fields), so these docs use margin for technical references. It mirrors the existing event contract API, so if you’re already integrated there you’re most of the way there: the margin endpoints follow the same patterns, authentication, and conventions, just under /margin.
Connectivity
REST API
| Environment | Base URL |
|---|
| Demo | https://external-api.demo.kalshi.co/trade-api/v2/margin/ |
| Production | https://external-api.kalshi.com/trade-api/v2/margin/ (rolling out member by member) |
external-api hosts for perps REST. WebSocket and FIX use the separate perps hosts listed below.
WebSocket API
| Environment | URL |
|---|
| Demo | wss://external-api-margin-ws.demo.kalshi.co/trade-api/ws/v2/margin |
| Production | wss://external-api-margin-ws.kalshi.com/trade-api/ws/v2/margin (rolling out member by member) |
FIX API
The margin FIX gateway uses a separate host from event contract FIX.
| Environment | Type | Host |
|---|
| Demo | Order entry and drop copy | margin-fix.demo.kalshi.co |
| Demo | Market data | margin-marketdata.fix.demo.kalshi.co |
| Production | Order entry and drop copy | margin-mm.fix.elections.kalshi.com |
| Production | Market data | margin-marketdata.fix.elections.kalshi.com |
| Purpose | Port | TargetCompID |
|---|
| Order Entry (without retransmission) | 8228 | KalshiNR |
| Drop Copy | 8229 | KalshiDC |
| Order Entry (with retransmission) | 8230 | KalshiRT |
| Market Data | 8233 | KalshiMD |
API Reference
The Perps API mirrors the event contract API (same auth, pagination, error format, and order lifecycle), so the conventions in Making Your First Request and API Environments apply directly.
- REST: see the REST reference in this section.
- WebSocket: see the margin channels under WebSockets in this section.
- FIX:
REST API
What’s the same: authentication, pagination, error format, and core order lifecycle (create, amend, decrease, cancel) all work identically, just under /margin/* instead of /portfolio/* and /markets/*.
Margin-specific additions: beyond the mirrored order, market, and order-group endpoints, margin adds endpoints for account balance and risk, funding (estimated and historical rates, plus payment history), fee tiers, subaccounts, and transfers between your event-contract and margin balances. See the REST reference for the full list. Two things to know up front: the event-contract ↔ margin transfer (/portfolio/intra_exchange_instance_transfer) is not yet available (enabled with the production rollout), and you can call /margin/enabled to check whether margin is on for your account in a given environment.
Not available on margin:
- Batch order operations (
BatchCreateOrders, BatchCancelOrders)
- Queue positions
- Events, series, milestones, multivariate collections, structured targets
- RFQs and quotes
- Historical data endpoints
- Exchange announcements and schedule
WebSocket API
Same channels: orderbook_delta, ticker, trade, fill, user_orders, order_group_updates
Not available on margin: market_positions, market_lifecycle_v2, multivariate_market_lifecycle, multivariate, communications
Timestamp convention: all timestamp fields in margin WebSocket payloads use Unix epoch milliseconds and an _ms suffix.
| Channel | Event contract | Margin |
|---|
orderbook_delta | ts as RFC3339 datetime | ts_ms as Unix milliseconds |
ticker | ts in Unix seconds and time as RFC3339 datetime | ts_ms (top level); nested reference_price/settlement_mark_price/liquidation_mark_price each carry ts_ms, and funding_rate carries next_funding_time_ms and ts_ms |
trade | ts in Unix seconds | ts_ms in Unix milliseconds |
fill | ts in Unix seconds | ts_ms in Unix milliseconds |
user_orders | created_time, last_update_time, expiration_time as RFC3339 datetimes | created_ts_ms, last_updated_ts_ms, expiration_ts_ms as Unix milliseconds |
Margin WebSocket payloads no longer use RFC3339 timestamp strings. The order_group_updates channel already follows the same convention: its only timestamp field, ts_ms, is Unix epoch milliseconds.
FIX API
API keys should not be shared between the event contract and margin FIX gateways.
| Event Contract FIX | Margin FIX |
|---|
| Pricing | Integer cents (1–99) | Decimal dollars up to 4 decimal places |
| Session types | 6 (NR, RT, DC, PT, RFQ, MD) | 4 (NR, RT, DC, MD) |
| RFQ / Quotes | Supported | Not available |
| Market settlement reports | Supported (on KalshiRT) | Not available |
| UseDollars (21005) | Optional logon flag | Always enabled (margin uses fixed-point dollar pricing by default) |
