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POST /api/v1/market/place-order
Auth required: Yes Buys outcome tokens by depositing base tokens (e.g., USDC) into the market’s APMM pool. The transaction is executed gaslessly via an ERC-4337 UserOperation.
This endpoint uses side: 1 for buying. For selling, see Sell Tokens (Withdraw).

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Request Body

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marketAddress
string
required
Prediction market contract address.
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optionAddress
string
required
Option token to buy (e.g., “Yes” or “No” token address).
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side
number
required
Must be 1 (buy/deposit).
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price
string
required
Price per token in base token units (6 decimal precision for USDC).
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amount
string
required
Amount of base tokens to spend (e.g., "10000000" = 10 USDC).
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minReceiveAmount
string
required
Minimum tokens to receive. Protects against slippage. If the actual output is less than this, the transaction reverts.
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deadline
string
required
Unix timestamp. Transaction reverts if not executed before this time.
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userOperation
object
required
Signed ERC-4337 UserOperation.

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Example

curl -X POST "https://api-staging.promethex.market/api/v1/market/place-order" \
  -H "Authorization: Bearer $PRIVY_JWT" \
  -H "Content-Type: application/json" \
  -d '{
    "marketAddress": "0x1234...abcd",
    "optionAddress": "0xaaaa...1111",
    "side": 1,
    "price": "650000",
    "amount": "10000000",
    "minReceiveAmount": "9500000",
    "deadline": "1740000000",
    "userOperation": {
      "sender": "0xSenderAddress...",
      "nonce": "0x01",
      "initCode": "0x",
      "callData": "0xCallData...",
      "callGasLimit": "0x30000",
      "verificationGasLimit": "0x20000",
      "preVerificationGas": "0x10000",
      "maxFeePerGas": "0x3B9ACA00",
      "maxPriorityFeePerGas": "0x3B9ACA00",
      "paymasterAndData": "0xPaymaster...",
      "signature": "0xSignature..."
    }
  }'

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Response

{
  "code": 0,
  "data": {
    "opHash": "0xabcdef...",
    "orderUuid": "order-123-456"
  }
}
​
opHash
string
UserOperation hash. Use to track the on-chain transaction status.
​
orderUuid
string
Internal order identifier.

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Execution Flow

Client                   PrometheX API            Bundler / Chain
  │                          │                         │
  ├── Build UserOp           │                         │
  ├── Sign UserOp            │                         │
  ├── POST /place-order ──► │                         │
  │                          ├── Validate order        │
  │                          ├── Submit to bundler ──► │
  │  ◄── { opHash } ─────── │                         │
  │                          │                         ├── Execute on-chain
  │                          │  ◄── Tx confirmed ──── │
  │  ◄── SSE: position_changed ─── │                  │
After confirmation, the user’s position is updated and an SSE event user:position_changed is emitted.
The userOperation must be properly constructed and signed via ERC-4337. See the Authentication page for details on signing.