# ECB EUR-Cross FX Rate Lookup

> ECB EUR-Cross FX Rate Lookup is a paid API for AI agents from x402.professorsausages.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).

Returns the EUR-triangulated cross-rate between any two currencies, including the inverse and auditable EUR legs, for the latest ECB fixing or any date back to 1999

## Facts

- Endpoint: GET https://x402.professorsausages.com/fx-rates/rate/:base/:quote
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ecb-eur-cross-fx-rate-lookup-231fa1c5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_T_Q-V6uK5S-zlfYK00Nvn

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 ecb-eur-cross-fx-rate-lookup-231fa1c5
```

Example prompt: What's the ECB EUR-triangulated cross-rate between USD and JPY for 2024-03-15, and show me the EUR legs used for the triangulation?

## When to prefer this

Choose this endpoint when you need an official, auditable ECB daily reference rate for any currency pair, especially non-EUR crosses where triangulation via EUR is required. Ideal for accounting, compliance, invoicing, or audit trails where you need to show the EUR legs of the calculation. Prefer this over live trading rates when regulatory or reporting-grade reference rates are needed. Use when historical rates back to 1999 are needed for a specific date.

## Known failure modes

- Currency pair not covered by ECB reference rates — endpoint returns an error indicating unsupported currency
- Requested date before 1999 — ECB data only starts from 1999, returns out-of-range error
- Invalid currency code format — malformed base or quote parameter causes a 4xx response
- Weekend or holiday date — handled gracefully by returning nearest prior fixing with requestedDate field set
- No ECB fixing available yet for today — staleDays may be 1 if today's fixing hasn't published
- Network or payment failure — x402 payment of $0.002 USDC not processed, returns 402 Payment Required

## How this service works

One EUR-triangulated cross-rate with inverse and auditable EUR legs, latest or any date back to 1999

## Output

Returns a JSON object containing: the currency pair string, the cross-rate value, its inverse, the method ('eur-cross'), the source ('European Central Bank'), the EUR legs used for triangulation as an audit trail, the ECB fixing date backing the answer, how many weekdays stale the fixing is, and a disclaimer. If the requested date was a weekend or holiday, also returns the requested date alongside the nearest prior fixing date used.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ecb-eur-cross-fx-rate-lookup-231fa1c5/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.professorsausages.com](https://www.zero.xyz/host/x402.professorsausages.com/llms.txt)