# tempo.halowerk.com – API Response Time to First Render (Renderstart)

> tempo.halowerk.com – API Response Time to First Render (Renderstart) 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).

Checks the time-to-first-render (visible render start) of an API response object at a given URL.

## Facts

- Endpoint: POST https://tempo.halowerk.com/v1/pruef/tempo/renderstart/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-api-response-time-to-first-render-renderstart-28b153a1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_VImmOVUu_1hljrkWlS--K

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-api-response-time-to-first-render-renderstart-28b153a1 -d '<json body>'
```

Example prompt: Can you check how long it takes for https://api.mysite.com/products to reach visible render start? I want to know the time-to-first-render for that API response.

## When to prefer this

Use this endpoint when you specifically need to measure the time-to-first-visible-render (renderstart) for an API response object, as opposed to a full page, iframe, video, or document. It is ideal for diagnosing perceived API performance bottlenecks at the render-start stage, distinct from DNS resolution time, total load time, or render-blocking resource counts.

## Known failure modes

- Target URL is unreachable or returns an error — endpoint cannot measure render start
- URL is not a public HTTP(S) address — validation failure
- Target does not produce a renderable response — no render start can be detected
- CSS selector matches no element — falls back to first matching object or returns error
- Request times out if the target is too slow to respond

## How this service works

Prüft am Objekt api-antwort den Befund Zeit bis zum sichtbaren Renderstart.

## Output

Returns a performance finding with the measured time (in milliseconds or seconds) until the API response object reaches visible render start, allowing developers to assess and optimize frontend rendering performance.

## 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-api-response-time-to-first-render-renderstart-28b153a1/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)