# Free Asset Radar x402 HMAC Utility

> Free Asset Radar x402 HMAC Utility is a paid API for AI agents from free-asset-radar-x402.besenok2018.workers.dev, paid per call via x402, $0.0005/call, status unknown (last checked 2026-10-18).

Computes an HMAC signature (hex and base64) using SHA-256 for a given input, edge-hosted for autonomous agents via x402 micropayment.

## Facts

- Endpoint: GET https://free-asset-radar-x402.besenok2018.workers.dev/api/x402/hmac?utm_source=zero.xyz
- Price: $0.0005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/free-asset-radar-x402-hmac-utility-3df70cd3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_rl2s3poKlxD5GWNB57uJ2

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 free-asset-radar-x402-hmac-utility-3df70cd3
```

Example prompt: Compute an HMAC SHA-256 signature for the message 'order:12345:confirmed' and give me both the hex and base64 output.

## When to prefer this

Choose this endpoint when you need a fast, edge-hosted HMAC SHA-256 computation accessible via x402 micropayment without managing your own crypto infrastructure. It is ideal for autonomous agents that need to sign or verify messages on-the-fly with minimal latency and no server setup. Prefer alternatives if you need HMAC with algorithms other than SHA-256, or if you require batch signing of many messages at once.

## Known failure modes

- Missing required input fields returns an error or malformed response
- Invalid property types in the request body may result in a 400 error
- Payment failure (insufficient USDC balance or x402 handshake error) blocks the request
- Cloudflare Worker cold start or edge outage may cause transient 503 errors
- Malformed JSON body may return an unparseable response

## How this service works

Stable edge-hosted x402 utilities for autonomous agents.

## Output

Returns a JSON object containing the HMAC signature in hexadecimal ('hex'), the algorithm used ('algo', e.g. 'sha256'), and the base64-encoded signature ('base64'). All three fields are computed from the provided input payload.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "required": {
   "type": "string"
  },
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "hex": "...",
  "algo": "sha256",
  "base64": "..."
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/free-asset-radar-x402-hmac-utility-3df70cd3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from free-asset-radar-x402.besenok2018.workers.dev](https://www.zero.xyz/host/free-asset-radar-x402.besenok2018.workers.dev/llms.txt)