# SelectaRank x402 Preflight Checker

> SelectaRank x402 Preflight Checker is a paid API for AI agents from selectarank-data.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-02).

Checks whether a given HTTPS URL is protected by x402 and returns its payment requirements before attempting a paid call

## Facts

- Endpoint: GET https://selectarank-data.vercel.app/v1/preflight?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/selectarank-x402-preflight-checker-81c129b9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IVssBPy5akhPNTmNIYvi2

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 selectarank-x402-preflight-checker-81c129b9
```

Example prompt: Before I call that paid data endpoint, can you run a preflight check on https://selectarank-data.vercel.app/v1/earthquakes to see if it's x402-protected and what payment options it accepts?

## When to prefer this

Use this endpoint when you need to programmatically discover whether a remote HTTPS endpoint requires x402 micropayment and what currencies/transport methods it accepts — especially before attempting an actual paid call. Prefer this over direct calling when you want to avoid unexpected payment failures or need to dynamically route payment logic in an agent workflow.

## Known failure modes

- Non-HTTPS or non-port-443 URL returns a validation error
- Endpoint is not publicly reachable, resulting in a connection error
- URL is not x402-protected, returning isStatus402: false with an empty accepts array
- Malformed URL input causes a 400-level error
- Timeout if the target endpoint is slow to respond

## How this service works

Pay-per-call access to public-domain data (USGS earthquakes, NOAA/NWS forecasts, World Bank indicators) plus an x402 endpoint pre-payment checker over x402 on Base USDC. No account or API key.

## Output

Returns a JSON object with the target URL, an array of accepted payment methods, a verdict string (e.g. 'ok'), the payment transport method (e.g. 'header'), and a boolean flag indicating whether the endpoint truly returns a 402 status. This lets callers understand payment requirements before committing funds.

## 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",
     "required": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string",
       "description": "https URL of the x402-protected endpoint to check (port 443, public host)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "url": "https://example.com/paid-endpoint",
  "accepts": [],
  "verdict": "ok",
  "transport": "header",
  "isStatus402": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/selectarank-x402-preflight-checker-81c129b9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from selectarank-data.vercel.app](https://www.zero.xyz/host/selectarank-data.vercel.app/llms.txt)