# Soren FX Oracle — ECB Reference Rate with Cryptographic Attestation

> Soren FX Oracle — ECB Reference Rate with Cryptographic Attestation is a paid API for AI agents from soren.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-12).

Returns a signed, timestamped European Central Bank reference exchange rate for any supported currency pair, including a SHA-256 hash and Ed25519 signature for verifiability.

## Facts

- Endpoint: GET https://soren.com/v1/oracle/fx?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/soren-fx-oracle-ecb-reference-rate-with-cryptographic-attestation-10ad784e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IvkvBnkJ4-wqBJoTBQcBd

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 soren-fx-oracle-ecb-reference-rate-with-cryptographic-attestation-10ad784e
```

Example prompt: Can you fetch me the current ECB reference exchange rate for EURUSD — I need it signed and timestamped so I can verify it later?

## When to prefer this

Choose this endpoint when you need a cryptographically attested, auditable FX rate traceable to ECB reference data — ideal for compliance workflows, smart contract oracles, financial audit trails, or any system where tamper-evidence matters. Prefer this over generic FX APIs when you need an Ed25519 signature and SHA-256 hash proving the exact data returned. Note that non-EUR pairs are crossed via EUR, which is disclosed in the response.

## Known failure modes

- Unsupported currency pair — ECB only publishes ~30 currencies, so exotic pairs will return an error
- Invalid pair format — must be exactly six uppercase letters (e.g. EURUSD), malformed input returns a 4xx error
- ECB data unavailability — if the ECB has not published rates for the current day (weekends, holidays), the latest available date is returned or an error is raised
- Network/payment failure — x402 payment of $0.01 USDC must succeed before the rate is returned

## How this service works

A signed, timestamped euro reference exchange rate from the European Central Bank, for any pair among the ~30 currencies it publishes. Returns the rate, the ECB reference date, the underlying euro base rates, a SHA-256 of the exact bytes returned, and an Ed25519 signature. Non-EUR pairs are crossed via EUR and that is stated in the response, because it is our calculation and not an ECB figure.

## Output

A JSON response containing: the requested currency pair rate, the ECB reference date, the individual EUR-based rates used to derive the figure, a SHA-256 hash of the exact response bytes, an Ed25519 signature for cryptographic verification, and a note if the rate was crossed via EUR (indicating it is Soren's calculation rather than a direct ECB figure).

## Request schema (JSON Schema)

```json
{
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "pair"
     ],
     "properties": {
      "pair": {
       "type": "string",
       "examples": [
        "EURUSD"
       ],
       "description": "Six-letter currency pair, e.g. EURUSD. Any pair among the ECB reference currencies; non-EUR pairs are crossed via EUR."
      }
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "value": {
   "pair": "EURUSD",
   "rate": "<number>",
   "derivation": "<text>",
   "reference_date": "<YYYY-MM-DD>"
  },
  "source": {
   "name": "European Central Bank",
   "notice": "Available free of charge from the ECB."
  },
  "provenance": {
   "signature": {
    "value": "<base64>",
    "algorithm": "Ed25519"
   },
   "observed_at": "<ISO-8601 UTC>",
   "upstream_sha256": "<hex>"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/soren-fx-oracle-ecb-reference-rate-with-cryptographic-attestation-10ad784e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from soren.com](https://www.zero.xyz/host/soren.com/llms.txt)