Trading Endpoints

Place orders, manage positions, and check balances across Polymarket and Kalshi.

All trading endpoints require the trade scope on your API key. Trading requests are never cached -- they are proxied directly to the exchange.

You must have exchange credentials stored before using trading endpoints. See Account > Exchange Credentials.

Orders

Create Order

POST /polymarket/orders
POST /kalshi/orders

Request body (CreateOrderParams):

Field	Type	Required	Description
`market_id`	string	Yes	Market identifier
`outcome_id`	string	Yes	Outcome to trade
`side`	string	Yes	`buy` or `sell`
`order_type`	string	Yes	`limit` or `market`
`amount`	string	Yes	Number of shares/contracts
`price`	string	For limit	Limit price (decimal string, e.g. `"0.65"`)
`time_in_force`	string	No	`GTC` (default), `IOC`, `FOK`

Polymarket example:

curl -X POST https://papi.tylerthebuildor.com/polymarket/orders \
  -H "Authorization: Bearer papi_sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "market_id": "0x1234abcd...",
    "outcome_id": "71234567890",
    "side": "buy",
    "order_type": "limit",
    "amount": "100.00",
    "price": "0.65",
    "time_in_force": "GTC"
  }'

Kalshi example:

curl -X POST https://papi.tylerthebuildor.com/kalshi/orders \
  -H "Authorization: Bearer papi_sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "market_id": "KXBTC-26DEC31-T100000",
    "outcome_id": "yes",
    "side": "buy",
    "order_type": "limit",
    "amount": "10.00",
    "price": "0.62",
    "time_in_force": "GTC"
  }'

Response (Order object):

{
  "id": "order_abc123",
  "market_id": "0x1234abcd...",
  "outcome_id": "71234567890",
  "side": "buy",
  "order_type": "limit",
  "price": "0.65",
  "amount": "100.00",
  "status": "open",
  "filled": "0.00",
  "remaining": "100.00",
  "timestamp": "2026-03-18T12:00:00Z",
  "fee": null,
  "time_in_force": "GTC"
}

List Orders

GET /polymarket/orders
GET /kalshi/orders

Parameter	Type	Description
`limit`	integer	Number of results
`pagination_key`	string	Cursor for pagination

curl -s "https://papi.tylerthebuildor.com/polymarket/orders?limit=10" \
  -H "Authorization: Bearer papi_sk_live_..."

Returns an array of Order objects.

Get Order

GET /polymarket/orders/{order_id}
GET /kalshi/orders/{order_id}

curl -s "https://papi.tylerthebuildor.com/polymarket/orders/order_abc123" \
  -H "Authorization: Bearer papi_sk_live_..."

Returns a single Order object.

Cancel Order

DELETE /polymarket/orders/{order_id}
DELETE /kalshi/orders/{order_id}

curl -X DELETE https://papi.tylerthebuildor.com/polymarket/orders/order_abc123 \
  -H "Authorization: Bearer papi_sk_live_..."

Positions

GET /polymarket/positions
GET /kalshi/positions

curl -s https://papi.tylerthebuildor.com/polymarket/positions \
  -H "Authorization: Bearer papi_sk_live_..."

Response (array of Position objects):

[
  {
    "market_id": "0x1234abcd...",
    "outcome_id": "71234567890",
    "outcome_label": "Yes",
    "size": "100.00",
    "entry_price": "0.55",
    "current_price": "0.72",
    "unrealized_pnl": "17.00",
    "realized_pnl": null,
    "market_title": "Will Bitcoin exceed $100k?",
    "market_slug": "will-bitcoin-exceed-100k",
    "redeemable": false
  }
]

Position Fields

Field	Type	Description
`market_id`	string	Market identifier
`outcome_id`	string	Outcome token/contract ID
`outcome_label`	string	Display label (e.g., "Yes")
`size`	string	Position size
`entry_price`	string	Average entry price
`current_price`	string	Current market price
`unrealized_pnl`	string	Unrealized profit/loss
`realized_pnl`	string \| null	Realized profit/loss
`market_title`	string	Market question text
`market_slug`	string	URL-friendly market identifier
`redeemable`	boolean	Whether the position can be redeemed

Balance

GET /polymarket/balance
GET /kalshi/balance

curl -s https://papi.tylerthebuildor.com/polymarket/balance \
  -H "Authorization: Bearer papi_sk_live_..."

Response (Balance object):

{
  "currency": "USDC",
  "total": "1000.00",
  "available": "850.00",
  "locked": "150.00"
}

Field	Type	Description
`currency`	string	Currency code (`USDC` for Polymarket, `USD` for Kalshi)
`total`	string	Total balance
`available`	string	Available for trading
`locked`	string	Locked in open orders

User Fills (Kalshi only)

GET /kalshi/trades/me

Returns your executed trades (fills) on Kalshi.

Parameter	Type	Description
`limit`	integer	Number of results

curl -s "https://papi.tylerthebuildor.com/kalshi/trades/me?limit=5" \
  -H "Authorization: Bearer papi_sk_live_..."

Returns an array of Trade objects representing your executed fills.

Order Type Reference

Field	Type	Values	Description
`side`	string	`buy`, `sell`	Order direction
`order_type`	string	`limit`, `market`	Order type
`status`	string	`open`, `filled`, `partially_filled`, `cancelled`	Order status
`time_in_force`	string	`GTC`, `IOC`, `FOK`	Time in force policy

GTC (Good Til Cancelled) -- Order remains open until filled or cancelled
IOC (Immediate or Cancel) -- Fill immediately or cancel unfilled portion
FOK (Fill or Kill) -- Fill entirely or cancel the whole order

Important Notes

All prices are decimal strings (e.g., "0.65", not 0.65 or 65)
Kalshi prices are automatically converted from cents -- you send and receive decimals
Order operations are never cached
Failed orders return exchange-specific error messages wrapped in the PAPI error format
You must have exchange credentials stored before using any trading endpoint

Trading

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