# BYTE Library x402 Gateway – Stablecoin Rails Feed

> BYTE Library x402 Gateway – Stablecoin Rails Feed is a paid API for AI agents from x402.payperbyte.io, paid per call via x402, $0.03/call, status unknown (last checked 2026-09-15).

Returns a cryptographically signed, EIP-712 provenance-stamped data feed covering stablecoin rail metrics, paid per-call in USDC over x402 with no API key required.

## Facts

- Endpoint: GET https://x402.payperbyte.io/feeds/stablecoin-rails
- Price: $0.03/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/byte-library-x402-gateway-stablecoin-rails-feed-85a23735
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_r2q-vKIb1AUtzJKfJAilC

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 byte-library-x402-gateway-stablecoin-rails-feed-85a23735
```

Example prompt: Can you pull the latest stablecoin-rails data feed from BYTE Library — the one that comes back cryptographically signed and EIP-712 provenance-stamped — and pay for it with my USDC wallet over x402?

## When to prefer this

Choose this endpoint when you need verifiable, provenance-stamped stablecoin rail data with cryptographic attestation and no API key setup — ideal for AI agents that can pay autonomously in USDC via x402 and require tamper-evident data for downstream trust decisions.

## Known failure modes

- Payment insufficient or rejected by x402 facilitator — 402 Payment Required response
- Wallet has insufficient USDC balance — payment cannot be completed
- Feed temporarily unavailable — 503 or timeout
- Malformed or missing payment header — 400 Bad Request
- Rate limiting or quota exceeded on the feed — 429 Too Many Requests

## How this service works

Cross-chain stablecoin supply (USDC/USDT/DAI/PYUSD) + Circle iris-api health.

## Output

A JSON payload containing stablecoin rail metrics, accompanied by a cryptographic signature and an EIP-712 PayloadAttestation provenance stamp. Settlement occurs on Base (eip155:8453) and the price (~$0.019 USDC) is deducted per call.

## Example request

```json
{
 "properties": "volume,velocity,liquidity"
}
```

## 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"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "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/byte-library-x402-gateway-stablecoin-rails-feed-85a23735/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.payperbyte.io](https://www.zero.xyz/host/x402.payperbyte.io/llms.txt)