# CelerAPI FX Historical Rate Lookup

> 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.

## Facts

- Endpoint: GET https://www.celerapi.com/v1/fx/rate/%7Bdate%7D
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/celerapi-fx-historical-rate-lookup-20eb160a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_TT3Qsbel9AjF8xJf_naFo

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability celerapi-fx-historical-rate-lookup-20eb160a
```

Example prompt: What was the EUR to USD exchange rate on January 15, 2025? Look it up using a structured historical FX rate source.

## When to prefer this

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.

## Known failure modes

- 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

## 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.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "pathParams": {
     "type": "object",
     "required": [
      "date"
     ],
     "properties": {
      "date": {
       "type": "string",
       "example": "2025-01-15",
       "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
       "examples": [
        "2025-01-15"
       ]
      }
     }
    },
    "queryParams": {
     "type": "object",
     "required": [
      "base_currency",
      "quote_currency"
     ],
     "properties": {
      "base_currency": {
       "type": "string",
       "example": "EUR",
       "pattern": "^[A-Z]{3}$",
       "examples": [
        "EUR"
       ]
      },
      "quote_currency": {
       "type": "string",
       "example": "USD",
       "pattern": "^[A-Z]{3}$",
       "examples": [
        "USD"
       ]
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "success",
      "complete",
      "data",
      "warnings",
      "provenance"
     ],
     "properties": {
      "data": {
       "type": "object",
       "required": [
        "date",
        "base_currency",
        "quote_currency",
        "rate",
        "provider_code"
       ],
       "properties": {
        "date": {
         "type": "string",
         "pattern": "^\\d{4}-\\d{2}-\\d{2}$"
        },
        "rate": {
         "type": "number",
         "exclusiveMinimum": 0
        },
        "base_currency": {
         "type": "string",
         "pattern": "^[A-Z]{3}$"
        },
        "provider_code": {
         "type": "string"
        },
        "quote_currency": {
         "type": "string",
         "pattern": "^[A-Z]{3}$"
        }
       },
       "additionalProperties": false
      },
      "success": {
       "const": true
      },
      "complete": {
       "type": "boolean"
      },
      "warnings": {
       "type": "array",
       "items": {
        "type": "object",
        "required": [
         "code",
         "message"
        ],
        "properties": {
         "code": {
    
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "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"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/celerapi-fx-historical-rate-lookup-20eb160a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from www.celerapi.com](https://www.zero.xyz/host/www.celerapi.com/llms.txt)