# TLS Protocol Version Checker

> TLS Protocol Version Checker is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-29).

Checks and returns whether the negotiated TLS protocol on port 443 is TLS 1.2 or TLS 1.3 for a given host or URL.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/tls-protocol?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/tls-protocol-version-checker-46612ffc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7Odj22RTt2fWRHwhbs5tK

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 tls-protocol-version-checker-46612ffc -d '<json body>'
```

Example prompt: Can you check what TLS protocol version is being negotiated on port 443 for api.example.com — I need to know if it's TLS 1.2 or TLS 1.3?

## When to prefer this

Use this endpoint when an agent needs to programmatically determine the negotiated TLS protocol version for a given domain or URL, particularly for security audits, compliance checks, or monitoring vendor/third-party API endpoints. Prefer the free sandbox alternative (/v1/sandbox/tls-protocol) first; use this paid endpoint when the sandbox is unavailable or rate-limited.

## Known failure modes

- Host unreachable or DNS resolution failure — endpoint cannot probe the target
- Non-443 port or non-HTTPS URL may not be supported
- SSRF-safe restrictions may block internal/private IP ranges
- Connection timeout if the remote host is slow to respond
- Invalid or malformed host/URL input returns a validation error

## How this service works

Call when an agent needs whether the negotiated protocol on port 443 is TLS 1.2 or 1.3. Exact $0.002 USDC. Prefer unpaid POST /v1/sandbox/tls-protocol first.

## Output

Returns the negotiated TLS protocol version (e.g. TLS 1.2 or TLS 1.3) for the specified host or URL on port 443, reflecting the actual handshake outcome between client and server.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "maxLength": 2048,
   "minLength": 8,
   "description": "Public URL whose hostname is inspected. Provide url or host. Private targets are rejected."
  },
  "host": {
   "type": "string",
   "examples": [
    "example.com"
   ],
   "maxLength": 253,
   "minLength": 1,
   "description": "Public hostname such as example.com. The port and check are fixed by the SKU. Provide host or url."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/tls-protocol-version-checker-46612ffc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)