# GW8 Signal API – Payment Rail Cost Checker

> GW8 Signal API – Payment Rail Cost Checker is a paid API for AI agents from micro-saas-agent.onrender.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-22).

Returns fee percentages, USD costs, settlement times, and a recommended rail for a given payment amount across Base USDC, XRPL RLUSD, and card rails

## Facts

- Endpoint: GET https://micro-saas-agent.onrender.com/api/rails?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/gw8-signal-api-payment-rail-cost-checker-09092733
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7TtUGaYiKd9RX9Ono_0X3

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 gw8-signal-api-payment-rail-cost-checker-09092733
```

Example prompt: I need to send $100 — can you check which payment rail is cheapest and fastest right now, comparing Base USDC, XRPL RLUSD, and card?

## When to prefer this

Use this endpoint when an AI agent or user needs to decide which payment rail to use for a specific USD amount, balancing cost vs speed. Prefer it over manual fee lookups when you need a single call that covers Base USDC, XRPL RLUSD, and card in one response with a built-in recommendation. Especially useful for x402-enabled agent workflows where rail choice affects operating costs at scale.

## Known failure modes

- Missing or invalid 'amount' query parameter returns error or empty rail list
- Service unavailable on Render free tier causing timeout or 503
- Stale fee data if upstream sources are slow to update (card fee is noted as static-estimate)
- No payment made on failure — charge only occurs after data is returned successfully

## How this service works

[Payment rails: fee + speed comparison] Cheapest and fastest payment rail right now for a USD amount (?amount=100): Base USDC (live gas x ETH/USD, ~2s), XRPL RLUSD/XRP (live fee x XRP/USD, ~3-5s), Tempo and Circle Arc (live gas, USD fees, ~1s), card (static 2.9% + $0.30, days). Fee USD/%, settlement time, sources, agent protocols per rail, recommended pick. Dead sources marked unavailable. 60s cache. $0.002 USDC. Signal only.

## Output

Returns a list of available payment rails (Base USDC, XRPL RLUSD, card) each with fee percentage, fee in USD, live/static status, and settlement time estimate. Also returns the queried amount, a recommended rail for cost efficiency, and the fastest rail for speed.

## 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": {
      "amount": {
       "type": "number",
       "example": 100
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {}
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "rails": [
   {
    "rail": "base-usdc",
    "feePct": 0.00095,
    "feeUsd": 0.00095,
    "status": "live",
    "settlement": "~2s"
   },
   {
    "rail": "xrpl-rlusd-xrp",
    "feePct": 0.000025,
    "feeUsd": 0.000025,
    "status": "live",
    "settlement": "~3-5s"
   },
   {
    "rail": "card",
    "feePct": 3.2,
    "feeUsd": 3.2,
    "status": "static-estimate",
    "settlement": "~1-3 business days"
   }
  ],
  "amountUsd": 100,
  "recommended": {
   "rail": "xrpl-rlusd-xrp",
   "fastest": "base-usdc"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/gw8-signal-api-payment-rail-cost-checker-09092733/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from micro-saas-agent.onrender.com](https://www.zero.xyz/host/micro-saas-agent.onrender.com/llms.txt)