Authentication & errors

API keysCopy Anchor Link

Keys look like lfx_live_ followed by 32 characters. Send yours in the x-api-key header (or Authorization: Bearer <key>).

curl https://api.landedfx.com/api/v1/usage -H "x-api-key: $LANDEDFX_KEY"

Endpoints that do work for you need a key: quotes, swap quotes, rate locks and carry quotes. Market data is public without one, at a lower rate limit. A key that is sent but not valid is always rejected, even on public endpoints, so a typo never fails silently.

We store only a hash of your key, so it is shown once, when it is issued. If you lose it, ask for a new one and we revoke the old one.

Plans and limitsCopy Anchor Link

Need more than Scale? Email hello@landedfx.com.

Upgrade under Plan and billing in the dashboard. You pay in USDC on Base from your wallet, and the plan applies to all your keys within a minute. Payments don't renew by themselves: we email you 7 days and 1 day before a plan ends, and your keys keep their limits for 3 more days before moving to Free. Moving up credits the unused part of your current plan. See Fees.

Every call made with your key counts toward the month, except calls rejected for rate limiting. Months run in UTC and reset on the 1st.

Responses carry your limits in headers:

UsageCopy Anchor Link

GET /usage returns your plan, calls this month, what's left, when it resets, and calls broken down by endpoint and by day.

{
  "code": 200,
  "message": "Usage retrieved successfully",
  "data": {
    "key": { "keyId": "key_a3f08cd4ce47", "name": "Acme Remit, production" },
    "month": "2026-11",
    "plan": { "id": "sandbox", "label": "Free", "ratePerMinute": 60, "monthlyCalls": 5000 },
    "calls": 2,
    "remaining": 4998,
    "resetsAt": "2026-12-01T00:00:00.000Z",
    "byRoute": [{ "route": "POST /forwards", "calls": 1, "errors": 0 }],
    "byDay": [{ "day": "2026-11-07", "calls": 2, "errors": 0 }]
  }
}

The envelopeCopy Anchor Link

Every response, success or error, has the same shape:

{
  "code": 201,
  "message": "Quote generated successfully",
  "data": { "…": "…" }
}

Validation errors add an errors array:

{
  "code": 400,
  "message": "Validation failed",
  "errors": ["amount must be a positive decimal with up to 18 decimals"]
}

AmountsCopy Anchor Link

Amounts are decimal strings ("150000", "725.50"), never JSON numbers, so nothing is lost to floating point.

ErrorsCopy Anchor Link