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Overview

As a builder, you route orders for your end-users using impersonation. Every order endpoint works the same as for regular traders — you just add the X-Builder-Customer-Id header.
Before routing orders, ensure the end-user has been onboarded to the target exchange. See User Management.

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Placing an order

POST /api/v1/orders?exchange={exchange}

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Parameters

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exchange
string
required
Exchange identifier: polymarket or kalshi.
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X-API-Key
string
required
Your builder API key.
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X-Builder-Customer-Id
string
required
The end-user’s customer_id.
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market_id
string
required
Exchange-native market ID.
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outcome
string
required
"Yes" or "No" (binary), or outcome name (categorical).
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side
string
required
"buy" or "sell".
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price
number
required
Limit price (0.01–0.99 for binary).
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size
number
required
Number of contracts.
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params
object
Optional exchange-specific parameters.
KeyValuesDescription
order_typegtc (default), ioc, fokTime-in-force / execution type
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credentials
object
Optional per-request credentials. Skips stored credentials.

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Response

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id
string
Order identifier.
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market_id
string
Market the order was placed on.
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outcome
string
The outcome being traded.
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side
string
"buy" or "sell".
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price
number
Order price.
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size
number
Total order size.
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filled
number
Amount filled so far.
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status
string
pending, open, filled, partially_filled, cancelled, or rejected.
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created_at
string
ISO 8601 creation timestamp.
curl -X POST "https://api.parsecapi.com/api/v1/orders?exchange=polymarket" \
  -H "X-API-Key: pk_live_YOUR_BUILDER_KEY" \
  -H "X-Builder-Customer-Id: CUSTOMER_ID" \
  -H "Content-Type: application/json" \
  -d '{
    "market_id": "0x1234abcd",
    "outcome": "Yes",
    "side": "buy",
    "price": 0.55,
    "size": 100
  }'

{
  "id": "order_abc123",
  "market_id": "0x1234abcd",
  "outcome": "Yes",
  "side": "buy",
  "price": 0.55,
  "size": 100,
  "filled": 0,
  "status": "open",
  "created_at": "2026-02-24T15:30:00Z"
}

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Placing an order with fee escrow

To collect fees on an order, include the fee_auth object signed by the end-user’s wallet. See Fee Escrow for details. 
curl -X POST "https://api.parsecapi.com/api/v1/orders?exchange=polymarket" \
  -H "X-API-Key: pk_live_YOUR_BUILDER_KEY" \
  -H "X-Builder-Customer-Id: CUSTOMER_ID" \
  -H "Content-Type: application/json" \
  -d '{
    "market_id": "0x1234abcd",
    "outcome": "Yes",
    "side": "buy",
    "price": 0.55,
    "size": 100,
    "fee_auth": {
      "order_id": "0xabc123...",
      "payer": "0xUserWalletAddress",
      "fee_amount": "250000",
      "deadline": 1740500000,
      "signature": "0x..."
    },
    "payer_address": "0xUserWalletAddress",
    "signer_address": "0xUserWalletAddress"
  }'

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Listing orders

GET /api/v1/orders?exchange={exchange} 
curl "https://api.parsecapi.com/api/v1/orders?exchange=polymarket" \
  -H "X-API-Key: pk_live_YOUR_BUILDER_KEY" \
  -H "X-Builder-Customer-Id: CUSTOMER_ID"

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Getting an order

GET /api/v1/orders/:order_id?exchange={exchange} 
curl "https://api.parsecapi.com/api/v1/orders/ORDER_ID?exchange=polymarket" \
  -H "X-API-Key: pk_live_YOUR_BUILDER_KEY" \
  -H "X-Builder-Customer-Id: CUSTOMER_ID"

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Cancelling an order

DELETE /api/v1/orders/:order_id?exchange={exchange} If fee escrow is active on the order, the escrowed fee is automatically refunded to the payer’s wallet on cancellation. 
curl -X DELETE "https://api.parsecapi.com/api/v1/orders/ORDER_ID?exchange=polymarket" \
  -H "X-API-Key: pk_live_YOUR_BUILDER_KEY" \
  -H "X-Builder-Customer-Id: CUSTOMER_ID"

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Other endpoints

All standard Parsec endpoints work with builder impersonation:
EndpointMethodDescription
/positionsGETList end-user’s positions
/balanceGETGet end-user’s balance
/fillsGETGet end-user’s trade history
/orderbookGETGet orderbook (no impersonation needed)
/marketsGETList markets (no impersonation needed)
/pingGETCheck exchange connectivity
Read-only market data endpoints (/markets, /orderbook, /trades, /price, /events) do not require X-Builder-Customer-Id — they work with just your builder API key.

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Order types

TypeBehaviorSupported
gtcGood-til-cancelled (default)All exchanges
iocImmediate-or-cancelPolymarket, Kalshi
fokFill-or-killPolymarket
Set via params.order_type in the create order request body. Unsupported combinations return 501.

Fee Escrow

Collect fees on every order.

Builder Tiers

See how your revenue share scales with volume.