# SALT19 URL HTTP Preflight Check

> SALT19 URL HTTP Preflight Check is a paid API for AI agents from api.salt19.com, paid per call via x402, $0.03/call, status unknown (last checked 2026-09-15).

Performs an HTTP preflight check on a given URL, returning final resolved URL, redirect count, latency, content type, and security header presence

## Facts

- Endpoint: POST https://api.salt19.com/v1/url-http-preflight
- 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/salt19-url-http-preflight-check-ccff518d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Qd6n8-OX1W8NWHh6vKSTB

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 salt19-url-http-preflight-check-ccff518d -d '<json body>'
```

Example prompt: Before I scrape this page, can you do a preflight check on https://example.com and tell me the final URL it resolves to, how many redirects there are, and whether it has security headers like HSTS and CSP in place?

## When to prefer this

Choose this endpoint when an agent needs to safely inspect a URL before acting on it — resolving redirects, confirming liveness, measuring latency, or auditing security posture — without fully downloading the page body. Particularly useful as a lightweight pre-step before web scraping, link validation pipelines, or security audits where you want HTTP metadata without full content retrieval.

## Known failure modes

- URL is unreachable or DNS fails — likely returns an error status or timeout
- Malformed URL input returns a validation error
- URL returns non-200 status (e.g. 404, 403) — status is reported but may indicate dead link
- Very high redirect chains may be truncated or cause timeout
- SSL/TLS errors on the target URL may cause connection failure

## How this service works

SALT19 is an independent applied AI systems lab behind EvoMind governed cognition, the MCP-native Agent Utility Grid, the ARCS research community, AeroClear UAS flight intelligence, and practical software for real-world work.

## Output

Returns a JSON object with the HTTP status code of the final response, the fully resolved final URL after all redirects, the number of redirects followed, round-trip latency in milliseconds, the content-type header value, and a set of boolean flags indicating presence of key security headers including x-content-type-options, content-security-policy, and strict-transport-security.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "format": "uri",
   "maxLength": 2048
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "status": 200,
  "final_url": "https://example.com/",
  "redirects": 0,
  "latency_ms": 110,
  "content_type": "text/html",
  "security_headers": {
   "x_content_type_options": true,
   "content_security_policy": false,
   "strict_transport_security": true
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/salt19-url-http-preflight-check-ccff518d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.salt19.com](https://www.zero.xyz/host/api.salt19.com/llms.txt)