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CelerAPI FX Historical Rate Lookup
x402
CelerAPI FX Historical Rate Lookup is a paid API for AI agents from www.celerapi.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).
Returns the foreign exchange rate between two currencies for a specific historical date, sourced from the European Central Bank via Frankfurter.
Price / call$0.002
Success—
StatusUnknown
How this service works
Resolve companies, legal entities and financial reference data using authoritative sources. Machine-native, pay per request, no subscription.
Output
A JSON object containing the exact exchange rate (as a positive number) between the requested base and quote currencies on the specified date, along with the date, currency codes, provider code, and full provenance metadata including source, license, provider name, source URL, freshness indicator, and retrieval timestamp.
Example use cases
Invoice reconciliation for past transactions
“I need to know the official EUR to GBP exchange rate on March 10, 2025 — I'm reconciling some invoices from that date and need the ECB reference rate.”
Historical portfolio valuation
“What was the USD to JPY exchange rate on December 31, 2024? I need it to calculate the year-end value of a yen-denominated asset in dollar terms.”
Expense report currency conversion
“Can you find the CHF to USD rate for February 5, 2025? I have some Swiss franc expenses from a business trip that I need to convert for my expense report.”
Technical details
Endpoint
GEThttps://www.celerapi.com/v1/fx/rate/%7Bdate%7DWhen to prefer
Choose this endpoint when you need a reliable, sourced historical FX rate for a specific past date between two currencies, especially for financial reporting, accounting reconciliation, or audit-trail purposes. It is ideal when you need provenance metadata (source, license, freshness) alongside the rate. Prefer this over generic FX APIs when you need ECB reference rates specifically, or when a micropayment-per-request model (no subscription or API key) fits your architecture.
Side effects
- Date not available — ECB does not publish rates for weekends or public holidays; response may be incomplete or return nearest available date
- Invalid currency code — non-ISO 4217 three-letter uppercase codes will fail validation
- Future dates — rates are not available for dates beyond today
- Unsupported currency pair — not all currency pairs are covered by ECB reference rates
- Network or upstream provider error from Frankfurter API
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"data": {},
"success": true,
"complete": true,
"warnings": [],
"provenance": {
"source": "European Central Bank reference rates via Frankfurter",
"license": "Frankfurter MIT; underlying ECB terms apply",
"provider": "frankfurter",
"freshness": "reference",
"source_url": "https://api.frankfurter.dev"
}
}
}Tags
x402
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