# CRC16-CCITT Checksum (Hex) Calculator

> CRC16-CCITT Checksum (Hex) Calculator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-02).

Computes the CRC16-CCITT checksum of input text and returns it as a hexadecimal string, with no network or LLM involvement.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/checksum-crc16-ccitt-hex?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/crc16-ccitt-checksum-hex-calculator-2beff3c9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_LclN0XPlGOGXT_hzA3YY0

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 crc16-ccitt-checksum-hex-calculator-2beff3c9 -d '<json body>'
```

Example prompt: Can you compute the CRC16-CCITT checksum in hex for this text: 'Hello, World!'?

## When to prefer this

Choose this endpoint when you need a fast, deterministic CRC16-CCITT hex checksum for data integrity verification, protocol framing, or deduplication, and you want a hosted computation with no dependencies on LLMs or external networks. Prefer the free sandbox endpoint (/v1/sandbox/checksum-crc16-ccitt-hex) for testing; use this paid endpoint for production workloads.

## Known failure modes

- Empty or missing text field returns a validation error
- Text exceeding 100,000 characters is rejected
- Invalid or missing API key returns an authentication error
- Malformed request body returns a 400 Bad Request

## How this service works

Call when an agent needs a crc16-ccitt checksum of text as hex. No network and no LLM. Exact $0.003 USDC. Prefer unpaid POST /v1/sandbox/checksum-crc16-ccitt-hex first.

## Output

Returns the CRC16-CCITT checksum of the provided text as a hexadecimal string (e.g. '29B1'). The computation is fully deterministic, requires no external network calls, and produces no side effects.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "key": {
   "type": "string",
   "maxLength": 512,
   "minLength": 1,
   "description": "HMAC secret. Required on HMAC SKUs. Omit it for plain digests and checksums. The key is not stored."
  },
  "text": {
   "type": "string",
   "examples": [
    "hello"
   ],
   "maxLength": 100000,
   "minLength": 1,
   "description": "Message to digest. For raw-hex SKUs this is hex bytes; for utf16 or latin1 SKUs it is decoded with that encoding. Otherwise it is UTF-8 text."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/crc16-ccitt-checksum-hex-calculator-2beff3c9/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)