Entropy L402 API

Cryptographic random bytes from hardware RNG.

5-10 sats per call, paid over the Lightning Network. No API key and no signup: the first request answers 402 Payment Required with a Lightning invoice, and repeating the request with the proof of payment returns your data.

l402_entropy 5-10 sats

Parameters

bytes 32-256 format hex/base64

Call it with curl

The first call answers 402 with a Lightning invoice in the WWW-Authenticate header. Pay it from any Lightning wallet, then repeat the call with the L402 token and preimage.

cURL

curl -X POST https://lightningfaucet.com/api/ \
  -H "Content-Type: application/json" \
  -H "Authorization: L402 $MACAROON:$PREIMAGE" \
  -d '{"action":"l402_entropy","bytes":32,"format":"hex"}'

What comes back

A successful call returns JSON, with the delivered content merged over the standard L402 receipt fields. Example values, not live data.

JSON

{
    "success": true,
    "http_code": 200,
    "service": "entropy",
    "timestamp": "2026-09-11T15:04:05+00:00",
    "paid_sats": 5,
    "entropy": "7c4a8d09ca3762af61e59520943dc26494f8941b1a3e5c7d9f0b2648ac135e79",
    "bytes": 32,
    "format": "hex",
    "source": "PHP random_bytes (CSPRNG)"
}

Call it from an AI agent

With lightning-wallet-mcp the payment is handled for you. From the CLI:

Terminal

lw pay-api "https://lightningfaucet.com/api/l402/entropy?bytes=32&format=hex"

In Claude Code, Cursor or any MCP host, ask the agent to call pay_l402_api with that URL. The fee is 1% of the price, rounded down, so calls under 100 sats carry no platform fee.

Questions

How much does the Entropy API cost?
Each call costs 5-10 sats, paid as a Lightning invoice at request time. There is no subscription, no minimum and no monthly bill: you are charged for the calls you make.

Do I need an API key or an account?
No. Payment is the authentication. The first request answers 402 Payment Required with a Lightning invoice; settling it returns a preimage that authenticates the retry.

What does Entropy return?
A JSON object carrying entropy, bytes, format and source. See the example response above for the exact shape.

Related endpoints

Random Sats 50 sats Precise Time 10 sats Request Echo 5 sats UUID Generator 5 sats Ask a Human 500 sats Ask a Human: Result Free

All Utility APIs endpoints · How L402 authentication works · List your own API on the gateway