Gassless swap giving "missing parameter" error

[umerrdev]

Hi there,

I’m trying to perform a gasless swap on Base network, either

from USDC → Virtual, or

from USDC → USDT.

However, every attempt to call the swap API fails with the following response:

{ "error_code": 100, "message": "missing parameter" }

What I’ve tried

Verified that all required fields (tokenIn, tokenOut, amount, slippage, chainId, userAddress, permit data, etc.) are included.

Tested both GET and POST methods where applicable.

Attempted with multiple parameter formats (camelCase, snake_case).

Confirmed API key and wallet addresses are valid.

Environment

Network: Base

Tokens: USDC → Virtual / USDC → USDT

Language/SDK: JavaScript (Node / Axios)

Response status: 201

API version: latest

{ "from": "0xxx", "to": "0xxx", "data": "0x90411a320000000000000000000000002691f337abeb0146f16441ca4f82f363275851d5000000000000000000000000000000000000000000000000000000000000006000000000000000000000000000000000000000000000000000000000000001c0000000000000000000000000833589fcd6edb6e08f4c7c32d4f71b54bda02913000000000000000000000000fde4c96c8593536e31f229ea8f37b2ada2699bb20000000000000000000000002691f337abeb0146f16441ca4f82f363275851d5000000000000000000000000b1dd8e9ebbf5f150b75642d1653df0dacd0bff4700000000000000000000000000000000000000000000000000000000000186a0000000000000000000000000000000000000000000000000000000000000c35600000000000000000000000000000000000000000000000000000000000186ad0000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000014000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000800000000000000000000000000000000000000000000000000000000000000104e5b07cdb000000000000000000000000b7f084c7f7f1c680d08780e2b2ef4f2133db0df8000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000186a0000000000000000000000000b1dd8e9ebbf5f150b75642d1653df0dacd0bff4700000000000000000000000000000000000000000000000000000000000000a0000000000000000000000000000000000000000000000000000000000000002e833589fcd6edb6e08f4c7c32d4f71b54bda029130001f4fde4c96c8593536e31f229ea8f37b2ada2699bb200000100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000", "amountDecimals": 100000, "feeAmount1": 4840, "feeAmount2": 4830, "flag": 2, "gasPriceDecimals": 2229716, "deadline": 1762042260, "inToken": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913", "outToken": "0xfde4c96c8593536e31f229ea8f37b2ada2699bb2", "nonce": 5, "permit": "0x30f20000000000000", "hash": "0xe76982c09198885d423073613b3268e276ec03e1caffa015eafkkc4387448c83" }