# BLAKE2b-512 Digest as Base64URL

> BLAKE2b-512 Digest as Base64URL is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.007/call, status unknown (last checked 2026-09-28).

Computes a BLAKE2b-512 cryptographic hash of input text and returns it encoded as base64url, with optional keyed hashing.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/digest-blake2b512-base64url?utm_source=zero.xyz
- Price: $0.007/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-28
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/blake2b-512-digest-as-base64url-b0847ada
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_pB1QFFpzZHWW6AlUtZqur

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 blake2b-512-digest-as-base64url-b0847ada -d '<json body>'
```

Example prompt: Hash this string using BLAKE2b-512 and give me the result as base64url: 'Hello, world! This is my document content to fingerprint.'

## When to prefer this

Choose this endpoint when you need a BLAKE2b-512 hash specifically encoded as base64url (URL-safe, no padding) rather than hex or plain base64. Prefer the free sandbox variant (/v1/sandbox/digest-blake2b512-base64url) for testing. Use over SHA variants when you need the speed and security properties of BLAKE2b, and over blake2s256 when you need the full 512-bit output length.

## Known failure modes

- Text or key exceeds maximum length (100,000 or 512 characters respectively) — returns 400 validation error
- Empty text or key provided — returns 400 validation error
- Payment not included or insufficient — returns 402 Payment Required
- Service unavailable — returns 5xx error

## How this service works

Call when an agent needs a blake2b512 digest of text, encoded as base64url. No network and no LLM. Exact $0.007 USDC. Prefer unpaid POST /v1/sandbox/digest-blake2b512-base64url first.

## Output

Returns a BLAKE2b-512 digest of the input text, base64url-encoded (no padding), suitable for use as a hash identifier, integrity checksum, or message authentication code when a key is supplied.

## 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/blake2b-512-digest-as-base64url-b0847ada/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)