# ViewportWitness by Apex Labs – Browser Assertion Verifier

> ViewportWitness by Apex Labs – Browser Assertion Verifier is a paid API for AI agents from qa.honeygate.app, paid per call via x402, $0.1/call, status unknown (last checked 2026-10-14).

Submits a public URL and a set of assertions for read-only browser verification across three viewport sizes, returning a queued check job with a poll URL

## Facts

- Endpoint: POST https://qa.honeygate.app/v1/verify?utm_source=zero.xyz
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/viewportwitness-by-apex-labs-browser-assertion-verifier-4f3f8446
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_x1k37haiOeXR4qAouBj0-

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 viewportwitness-by-apex-labs-browser-assertion-verifier-4f3f8446 -d '<json body>'
```

Example prompt: Can you verify that https://myapp.io/landing checks out on mobile, tablet, and desktop — specifically that the hero image is visible and the sign-up button is present in all three viewports?

## When to prefer this

Choose this endpoint when you need to validate that a publicly accessible web page meets specific UI or content assertions across three distinct viewport sizes (mobile, tablet, desktop) without operating your own headless browser infrastructure. It is especially useful for post-deploy smoke tests, CI quality gates, and cross-device layout verification where asynchronous (queued) results are acceptable.

## Known failure modes

- Non-public or non-HTTPS URLs will be rejected or fail to load
- Assertions array with fewer than 1 or more than 20 items will fail validation
- Slow or unresponsive target URLs may cause timeouts before results are available
- Polling the job URL too quickly may return a still-queued status
- Payment failure (x402) will prevent the check from being submitted

## How this service works

Machine-facing browser QA API. Submit a public HTTPS URL and receive screenshots, accessibility findings, layout analysis, and a structured report across three browser viewports. x402 payment is required per report on the live service; see /.well-known/x402 for current payment options. Self-hosted instances can run in test mode without payment.

## Output

Returns a JSON object containing a unique check ID (UUID), a status field (initially 'queued'), a poll URL to retrieve results once processing completes, and the active payment mode. The agent must poll the returned URL to get the full assertion results including screenshots and accessibility findings.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "format": "uri",
   "example": "https://example.com",
   "description": "Public HTTPS URL to check"
  },
  "assertions": {
   "type": "array",
   "items": {
    "type": "object",
    "description": "One of noHorizontalOverflow, noConsoleErrors, textVisible, titleIncludes, selectorExists, or selectorVisible."
   },
   "maxItems": 20,
   "minItems": 1,
   "description": "Explicit website assertions to evaluate across phone and desktop viewports."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": "550e8400-e29b-41d4-a716-446655440000",
  "status": "queued",
  "pollUrl": "/v1/checks/550e8400-e29b-41d4-a716-446655440000",
  "paymentMode": "production"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/viewportwitness-by-apex-labs-browser-assertion-verifier-4f3f8446/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from qa.honeygate.app](https://www.zero.xyz/host/qa.honeygate.app/llms.txt)