# Xynaptic Fiat-USDC Rate

> Xynaptic Fiat-USDC Rate is a paid API for AI agents from api.xynaptic.io, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-02).

Returns the best fiat-to-USDC conversion rate across Base, Polygon, and Solana payment rails, including live Coinbase spot price, bid-ask spread, network fees, slippage hint, and a best-rail verdict.

## Facts

- Endpoint: GET https://api.xynaptic.io/v1/fiat-usdc-rate?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/xynaptic-fiat-usdc-rate-48b5fe40
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ygYxgPxDQsuP3efJ-SVwQ

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 xynaptic-fiat-usdc-rate-48b5fe40
```

Example prompt: What's the best rate and cheapest rail to convert EUR to USDC right now — show me the live Coinbase spot price, estimated fees, and whether I should use Base, Polygon, or Solana?

## When to prefer this

Use this endpoint when an agent needs to programmatically determine the optimal payment rail and current cost to convert fiat (e.g. EUR) to USDC before executing an on-chain settlement. Preferred over generic FX APIs because it bundles cross-rail fee comparison and a concrete best-rail recommendation specifically for USDC stablecoin settlement on Base, Polygon, and Solana.

## Known failure modes

- Unsupported currency code returns an error or empty result
- Coinbase spot feed unavailable causes stale or missing rate
- Network fee estimation may lag real-time congestion
- Missing or invalid query parameter returns 400-level error
- Rate limiting may apply if called too frequently

## How this service works

Xynaptic Fiat-USDC Rate — best fiat↔USDC conversion rate per payment rail (Base, Polygon, Solana): live Coinbase spot EUR/USD with bid-ask spread, estimated network fees, slippage hint and best-rail verdict for agents settling in USDC. GET (?currency=EUR).

## Output

Returns the live Coinbase spot EUR/USD price, bid-ask spread, estimated network fees per rail (Base, Polygon, Solana), a slippage hint, and a best-rail verdict recommending which network to use for the most cost-effective USDC settlement.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/xynaptic-fiat-usdc-rate-48b5fe40/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.xynaptic.io](https://www.zero.xyz/host/api.xynaptic.io/llms.txt)