API documentation

Pass your API key as a bearer token. Keys come in two modes: sk_live_… bills credits against your quota, sk_test_… returns fixed mock rates and is free.

curl https://api.sync-convert.com/v1/rates/latest?base=EUR \
  -H "Authorization: Bearer sk_live_xxxxxxxxxxxx"

Keys are stored hashed — we can show you the prefix and last four characters, never the whole key again. Rotate from the dashboard if you lose one.

Every successful response carries provenance so you can decide whether a rate is fresh enough for your use case rather than trusting us blindly.

{
  "success": true,
  "base": "EUR",
  "rates": { "USD": 1.0842, "TRY": 47.3120 },
  "as_of": 1755950412338,
  "age_ms": 412,
  "source_tier": "licensed_ws",
  "stale": false,
  "meta": { "credits_used": 1, "credits_remaining": 29873 }
}

A source_tier of manual means the rate is a fixed figure we maintain by hand for a currency no connected source publishes — currently MAD. It is not live market data. A cross rate touching a manual leg is reported as manual, so you can branch on it if a pegged figure is not acceptable for your use case.

You are billed in call credits, not raw requests, so a cheap lookup costs less than an expensive one. Weights are per plan and visible in your dashboard.

Errors use a consistent shape. Messages are localised via the Accept-Language header (en, fr, ru, tr).

{
  "success": false,
  "error": {
    "code": "CURRENCY_NOT_ENABLED",
    "message": "TRY is not enabled for this tenant.",
    "doc_url": "https://sync-convert.com/docs#errors"
  }
}

Available on Pro and above. Connect, authenticate with your API key, then subscribe to the pairs you have enabled. Ticks arrive as they land — no polling, and streaming does not consume request credits beyond the per-pair daily subscription charge.

const ws = new WebSocket("wss://stream.sync-convert.com/v1");

ws.onopen = () => {
  ws.send(JSON.stringify({ type: "auth", key: "sk_live_xxxxxxxxxxxx" }));
  ws.send(JSON.stringify({ type: "subscribe", pairs: ["EUR/TRY", "BTC/USD"] }));
};

ws.onmessage = (event) => {
  const tick = JSON.parse(event.data);
  // { pair: "EUR/TRY", rate: 47.3120, as_of: 1755950412338 }
};