Exchange Rates API

Live mid-market rates, exact conversions and 5-year daily history — the same data behind our calculator. All amounts are computed with integer-scaled arithmetic (no float drift) and returned as decimal strings.

Authentication

Pass your key as the X-Api-Key header (or ?apikey=). To get a key, email api@fxconverter.tech.

Tier	Requests / day	Price
Free	1,000	$0
Pro	100,000	Contact us

Remaining quota is returned on every response in X-RateLimit-Remaining.

Endpoints

GET/api/v1/rate

Live mid-market rate for one pair (10-minute cache; falls back to last stored rate with stale:true).

curl -H "X-Api-Key: fxc_..." \
  "https://fxconverter.tech/api/v1/rate?from=USD&to=EUR"

{ "pair": "USDEUR", "from": "USD", "to": "EUR",
  "rate": "0.8756", "asOf": "2026-07-06T09:40:00.000Z", "stale": false }

GET/api/v1/convert

Convert an amount with integer-exact arithmetic. Amounts and results are decimal strings.

curl -H "X-Api-Key: fxc_..." \
  "https://fxconverter.tech/api/v1/convert?from=USD&to=EUR&amount=1234.56"

{ "from": "USD", "to": "EUR", "amount": "1234.56",
  "rate": "0.8756", "result": "1080.98", "asOf": "...", "stale": false }

GET/api/v1/history

Daily history (ranges: 1m, 3m, 6m, 1y, 5y) with best/worst/average stats. Add &format=csv for CSV.

curl -H "X-Api-Key: fxc_..." \
  "https://fxconverter.tech/api/v1/history?from=USD&to=EUR&range=1y"

{ "pair": "USDEUR", "range": "1y", "count": 261,
  "points": [{ "date": "2025-07-07", "rate": "0.8493" }, ...],
  "stats": { "best": "0.8830", "worst": "0.8317", "average": "0.8590",
             "changePct": 3.1, "currentVsAveragePct": 1.9 } }

Notes

Rates are mid-market; the money you actually receive from a bank or transfer service will include their margin.
Any-to-any pairs are supported; the first request for an exotic pair may take a moment while its history is backfilled.
No forecasts. If you need a forward-looking number, use the historical volatility from the history stats — not a prediction.