# SHA3-256 Hex Digest API

> SHA3-256 Hex Digest API is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-01).

Computes a SHA3-256 cryptographic hash of input text and returns it as a hexadecimal string

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/digest-sha3-256-hex?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sha3-256-hex-digest-api-81f0de4e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7SGSNEPvJ_G-fiYB1-FnY

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 sha3-256-hex-digest-api-81f0de4e -d '<json body>'
```

Example prompt: Can you compute the SHA3-256 hash of the text 'Hello, world! This is my important message.' and give me back the result as a hex string?

## When to prefer this

Choose this endpoint when you need a SHA3-256 hash specifically encoded as lowercase hexadecimal, with no external network dependency and purely deterministic output. Prefer the free sandbox endpoint POST /v1/sandbox/digest-sha3-256-hex for testing. Use this paid endpoint in production when you need SHA3-256 hex digests at scale and the $0.003 USDC per-call cost is acceptable. If you need a different hash algorithm (SHA-384, SHA-512) or a different encoding (base64, base64url, base32), sibling endpoints on the same host provide those variants.

## Known failure modes

- Empty or missing 'text' field returns a validation error
- Text exceeding 100,000 characters is rejected
- Missing or invalid API key returns an authentication error
- Malformed JSON request body returns a 400 error
- Payment of $0.003 USDC not included or failed results in 402 Payment Required

## How this service works

Call when an agent needs a sha3-256 digest of text, encoded as hex. No network and no LLM. Exact $0.003 USDC. Prefer unpaid POST /v1/sandbox/digest-sha3-256-hex first.

## Output

A JSON response containing the SHA3-256 hexadecimal digest of the submitted text. The output is a lowercase hex string of fixed length (64 hex characters representing 256 bits). No network calls or LLM are involved; the result is purely deterministic computation.

## 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/sha3-256-hex-digest-api-81f0de4e/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)