POST /v1/swap/build

Build an unsigned swap transaction. You sign it client-side, then submit via POST /v1/swap.

Request

POST /v1/swap/build
Content-Type: application/json
X-API-Key: YOUR_API_KEY

Body

Field	Type	Required	Default	Description
inputMint	string	Yes	—	Base58 mint or token symbol (e.g. "SOL", "USDC")
outputMint	string	Yes	—	Base58 mint or token symbol
amount	string	Yes	—	Amount in smallest units
slippageBps	number	No	100	Slippage tolerance (1-5000 bps)
userPublicKey	string	Yes	—	Base58 public key of the signer
createAtaIfMissing	boolean	No	true	Create input/output token accounts if they don't exist

Example

{
  "inputMint": "SOL",
  "outputMint": "USDC",
  "amount": "1000000000",
  "slippageBps": 100,
  "userPublicKey": "7xKXtg2CW87d97TXJSDpbD5jBkheTqA83TZRuJosgAsU"
}

Full mint addresses also accepted:

{
  "inputMint": "So11111111111111111111111111111111111111112",
  "outputMint": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
  "amount": "1000000000",
  "slippageBps": 100,
  "userPublicKey": "7xKXtg2CW87d97TXJSDpbD5jBkheTqA83TZRuJosgAsU"
}

Response

200 OK

{
  "transaction": "AQAAAA...base64...==",
  "quoteId": "q_42_1712000000000",
  "route": {
    "dex": "orca-whirlpool",
    "poolAddress": "HJPjoWUr...",
    "outputAmount": "134520000"
  },
  "estimatedOutput": "134520000",
  "minOutput": "133174800",
  "feeLamports": "5000000",
  "feeBps": 50,
  "computeUnits": 400000
}

Response Fields

Field	Type	Description
transaction	string	Base64-encoded unsigned VersionedTransaction
quoteId	string	Quote identifier — required for submission (30s TTL)
route	object	Selected route details
estimatedOutput	string	Expected output in smallest units
minOutput	string	Minimum output after slippage
feeLamports	string	Venum fee in input token units
feeBps	number	Fee rate in basis points
computeUnits	number	Allocated compute units

Transaction Contents

The unsigned transaction contains:

1. SetComputeUnitLimit — sized per DEX type (200K-600K CU)
2. ATA creation (if createAtaIfMissing: true and account missing) — idempotent createAssociatedTokenAccount for input/output tokens
3. Swap instruction(s) — DEX-specific swap (may include tick/bin array init)

Set createAtaIfMissing: false if your token accounts are pre-created to skip the RPC check and keep transaction size minimal.

Errors

Status	Description
400	Invalid request body
401	Missing or invalid API key
404	No pools found or no valid quote
429	Rate limit exceeded
500	Failed to build swap instruction
503	Blockhash not available (retry in a moment)

Rate Limit

20 requests per minute per API key.