# VendSDK HTTP HEAD Probe

> VendSDK HTTP HEAD Probe is a paid API for AI agents from vendsdk.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).

Checks the public status, latency, and response headers of a given HTTPS URL via an HTTP HEAD request for uptime and health monitoring

## Facts

- Endpoint: GET https://vendsdk.com/api/v/http-head
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vendsdk-http-head-probe-99a3fc6c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_emZ1Alnab2BkRYpDRXnNr

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 vendsdk-http-head-probe-99a3fc6c
```

Example prompt: Can you ping https://api.example.com/health and tell me if it's up — I want the HTTP status code, how long it took to respond, and the main response headers?

## When to prefer this

Use this endpoint when you need a fast, lightweight reachability check for a public HTTPS URL without downloading any response body. It is ideal for uptime agents, health dashboards, header inspection, and latency baselining. Prefer it over a full GET fetch when you only care about status, latency, and headers — saving bandwidth and cost. It complements the sibling TLS cert and DNS endpoints for full infrastructure health bundles.

## Known failure modes

- URL is not a valid public HTTPS address — returns an error or no result
- Target host is unreachable or times out — returns ok: false with no status
- Non-public/internal URLs (e.g. localhost, RFC1918 addresses) blocked for SSRF safety
- Unexpected redirect chains may affect reported status
- Some servers block HEAD requests and return 405 Method Not Allowed

## How this service works

Public URL status, latency, and response header subset for uptime and health agents

## Output

Returns a JSON object containing: a boolean `ok` indicating whether the request succeeded, the HTTP `status` code (e.g. 200, 404, 503), response time in milliseconds (`ms`), a subset of response headers, and an optional `service` label. Does not return the response body.

## 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"
    },
    "pathParams": {
     "type": "object"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string",
       "description": "Public https:// URL"
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "ms": {
       "type": "number"
      },
      "ok": {
       "type": "boolean"
      },
      "status": {
       "type": "number"
      },
      "headers": {
       "type": "object"
      },
      "service": {
       "type": "string"
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vendsdk-http-head-probe-99a3fc6c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from vendsdk.com](https://www.zero.xyz/host/vendsdk.com/llms.txt)