# tempo.halowerk.com – TTFB Check for API Response

> tempo.halowerk.com – TTFB Check for API Response is a paid API for AI agents from tempo.halowerk.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Measures the Time To First Byte (TTFB) for an API response object at a given URL, returning performance benchmark data.

## Facts

- Endpoint: POST https://tempo.halowerk.com/v1/pruef/tempo/ttfb/api-antwort
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/tempo-halowerk-com-ttfb-check-for-api-response-9d19bb59
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_RBLuhahkl4J7bOQ88gx9k

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 tempo-halowerk-com-ttfb-check-for-api-response-9d19bb59 -d '<json body>'
```

Example prompt: Can you check the time to first byte for the API response at https://api.example.com/data and tell me how fast it starts responding?

## When to prefer this

Use this endpoint when you specifically need to measure Time To First Byte (TTFB) for an API response object — not a webpage, font, image, or stylesheet. It is specialized for API endpoint latency profiling. Prefer this over generic HTTP timing tools when you need structured, actionable TTFB findings compatible with the tempo.halowerk.com performance audit framework. It pairs naturally with sibling endpoints measuring connection setup time, DNS resolution, and TLS handshake for full network timing breakdowns.

## Known failure modes

- Target URL unreachable or returns non-200 status — measurement may fail or return error finding
- URL exceeds 2048 character limit — request rejected with validation error
- Private/internal IP addresses or non-public URLs rejected
- Slow or timing-out endpoints may produce incomplete TTFB data
- Invalid CSS selector format causes request failure
- DNS resolution failure for the target host

## How this service works

Prüft am Objekt api-antwort den Befund Zeit bis zum ersten Byte.

## Output

Returns a performance finding (Befund) for the TTFB (Zeit bis zum ersten Byte) of the targeted API response, including the measured time value and associated benchmark data indicating how quickly the server begins sending response data.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "ziel": {
   "oneOf": [
    {
     "type": "string",
     "maxLength": 2048,
     "minLength": 1,
     "description": "Öffentliche HTTP(S)-Adresse; bei DNS-Befunden Domain oder öffentliche IP."
    },
    {
     "type": "object",
     "required": [
      "adresse"
     ],
     "properties": {
      "adresse": {
       "type": "string",
       "maxLength": 2048,
       "minLength": 1
      },
      "selektor": {
       "type": "string",
       "maxLength": 240,
       "minLength": 1,
       "description": "CSS-Selektor: genau ein Objekt, sonst erster Treffer des Objektfilters."
      },
      "vergleich": {
       "type": "string",
       "maxLength": 2048,
       "description": "Öffentliche Vergleichsadresse für Link-, Sitemap- oder Sprachbefunde."
      },
      "user_agent": {
       "type": "string",
       "pattern": "^[A-Za-z0-9_-]{1,80}$"
      },
      "dkim_selektor": {
       "type": "string",
       "pattern": "^[A-Za-z0-9_-]{1,63}$"
      }
     },
     "additionalProperties": false
    }
   ]
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/tempo-halowerk-com-ttfb-check-for-api-response-9d19bb59/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from tempo.halowerk.com](https://www.zero.xyz/host/tempo.halowerk.com/llms.txt)