Quickstart

Create a free key, then get a priced route in one request.

Get a key

Sign in with a one-time code sent to your email, or with Google. Either creates the account. Answer four short questions, create a key, and the Free plan is active right away: 150,000 calls a month at 5 requests a second, no card.

The key is shown once. The database holds a hash of it and nothing else, so a lost key cannot be recovered. Revoke it and make another.

Make an authenticated call

bash

curl -X POST https://swap-api.lcx.com/v1/quote \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "chainId": 1,
    "tokenIn":  "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
    "tokenOut": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
    "amountIn": "1000000000000000000",
    "slippageBps": 50
  }'

Send the key in the Authorization header, never in a query string. Query strings end up in browser history, proxy logs and referrer headers.

Reading the response

json

{
  "success": true,
  "data": {
    "quote": {
      "quoteId": "q_1_2_1785331092",
      "chainId": 1,
      "blockNumber": 25638739,
      "expiresAt": 1785331212,
      "input":  { "amount": "1000000000000000000", "token": "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2" },
      "output": {
        "amount": "1900850015",
        "minimumAmount": "1891345764",
        "token": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"
      },
      "priceImpactPct": 0.05,
      "usdValueIn": 1901.8,
      "usdValueOut": 1900.85,
      "slippageBps": 50,
      "gasEstimateWei": "51205426350000",
      "gasFeeUSD": 0.0974,
      "venues": ["uniswap-v3"],
      "spender": "0x…",
      "stale": false
    }
  }
}

Amounts go in human and come back raw, as strings; see conventions. minimumAmount is the floor your slippageBps implies. Below it the swap reverts on-chain.

blockNumber pins the chain state this price was computed from, and expiresAt is 120 seconds after the quote was made. venues carries adapter keys in the spelling the engine uses internally, lowercase and hyphenated.

Next: Quotes & execution covers turning this into a transaction.

Introduction

Authentication