# 54ch10 Pre-Interact URL Check — Stack Purchase

> 54ch10 Pre-Interact URL Check — Stack Purchase is a paid API for AI agents from 54ch10.uk, paid per call via x402, $1/call, status unknown (last checked 2026-09-14).

Purchases a $1 USDC credit stack (pack of URL-check credits) that enables subsequent URL analysis calls via the 54ch10 analytics service

## Facts

- Endpoint: POST https://54ch10.uk/v1/stack
- Price: $1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/54ch10-pre-interact-url-check-stack-purchase-50315060
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_9Qc0MKkqbEfObD1TA48_G

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 54ch10-pre-interact-url-check-stack-purchase-50315060 -d '<json body>'
```

Example prompt: Buy me a $1 credit stack on 54ch10 so I can start checking URLs before I interact with them — I want to get the API header and see how many credits I have.

## When to prefer this

Use this endpoint first, before calling any 54ch10 URL-check endpoint, when you have no active credit stack or your credits have expired. This is the funding/onboarding step — it is not the URL analysis call itself. Prefer this over alternatives if you need pay-per-use, low-commitment access ($1 flat) to URL analytics without a subscription.

## Known failure modes

- Payment not received or insufficient USDC — no stack issued
- Expired or invalid payment token — returns error
- Credits from a prior purchase already expired before use — non-refundable
- Network timeout during payment processing — transaction may not complete
- Duplicate purchase attempts may result in multiple non-refundable stacks

## How this service works

54ch10: pre-interact URL check. Paste a link, get brief + domain + page. Taste /v1/open/free. 80 calls for $1. Wire in 30s. Analytics-only tooling. Not financial advice.

## Output

Returns a JSON object confirming the purchase with: a header value (X-54ch10-Stack) to use in subsequent API calls, the number of credits purchased (e.g. 80), the pack count, expiry date (TTL in days), amount paid in USD, and a disclaimer that credits are non-refundable and informational only.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "q": {
   "type": "string",
   "description": "Input"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "note": "Unused credits expire. NOT a vault. Not refundable.",
  "pack": 1,
  "header": "X-54ch10-Stack: abc123",
  "credits": 80,
  "expires": "2026-09-01T00:00:00.000Z",
  "paid_usd": "1.00",
  "ttl_days": 7,
  "disclaimer": "Informational tooling only. Not financial advice. No custody, trading, or token promotion. Scores are imperfect heuristics — verify independently."
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/54ch10-pre-interact-url-check-stack-purchase-50315060/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from 54ch10.uk](https://www.zero.xyz/host/54ch10.uk/llms.txt)