# Password Entropy Calculator

> Password Entropy Calculator is a paid API for AI agents from api.x402node.dev, paid per call via x402, $0.0022/call, status unknown (last checked 2026-09-14).

Calculates Shannon entropy, bits of randomness, and character set size for a given password to produce a mathematical password strength metric.

## Facts

- Endpoint: GET https://api.x402node.dev/password/entropy
- Price: $0.0022/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/api-x402node-dev-63f01f88
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__Gdhtz9NpwogOZrJVcaab

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 api-x402node-dev-63f01f88
```

Example prompt: What's the Shannon entropy and bits of randomness for the password 'Tr0ub4dor&3'? I need the charset size and entropy score for a security audit.

## When to prefer this

Use this endpoint when you need a precise, mathematical entropy-based strength measurement for passwords rather than a heuristic score. Ideal for security audits, compliance checks, or any workflow requiring quantitative password randomness analysis without relying on pattern-matching libraries.

## Known failure modes

- Empty password string returns error or zero entropy
- Extremely long passwords may be truncated or rejected
- Missing or malformed request body returns 400 error
- Payment failure (402) if USDC balance insufficient

## How this service works

Password entropy calculator, Shannon entropy, bits of randomness, charset size, mathematical password strength metric for security audits. Accepts payment on Base or Solana — either network works.

## Output

Returns Shannon entropy value in bits, total bits of randomness, character set size used in the password, and an overall mathematical password strength metric suitable for security audits.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "password": {
       "type": "string",
       "description": "Password (optional)"
      }
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/api-x402node-dev-63f01f88/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.x402node.dev](https://www.zero.xyz/host/api.x402node.dev/llms.txt)