NUT-24 / HTTP 402 + Cashu

Stop hard-coding paywalls. Ship HTTP-native micropayments.

402forDummies is a practical entry point to the NUT-24 flow. Your server responds with a standard 402 Payment Required, the client decodes the payment request, retries with cashuB, and unlocks access after validation.

Give me the TL;DRTry Interactive Demo
NUT-24
HTTP 402 payment negotiation
NUT-18
Encoded request structure
NUT-12
Token handling for clients

Flow that falls into place

Scroll through the request/response lifecycle used by NUT-24.

1Client requests protected resource
A normal HTTP request is sent without payment headers.
GET /premium/guide
Host: 402fordummies.com
2Server returns HTTP 402 + X-Cashu
The response contains a NUT-18 encoded payment request in a header.
HTTP/1.1 402 Payment Required
X-Cashu: eyJhIjoyMSwidSI6InNhdCIsIm0iOlt...
3Client decodes and evaluates request
The wallet checks amount, unit, accepted mints, and optional NUT-10 lock conditions.
decode(X-Cashu) -> { a, u, m, nut10 }
4Client retries with cashuB token
Token is built from a valid mint and sent in X-Cashu.
GET /premium/guide
X-Cashu: cashuB...
5Server validates payment
Mint, unit, amount, and lock conditions are checked before serving content.
HTTP/1.1 200 OK
(or 400 Bad Request on failure)

Interactive multi-step demo

Walk through the actual lifecycle: 402 header issuance, client-side decode, retry with payment token, and final server validation.

Current step: Ready

Step 1

Resource requested

Step 2

402 with X-Cashu

Step 3

Header decoded

Step 4

cashuB retry sent

Step 5

Server validation

Client Controls
Configure the client token before running validation.
Protocol Inspector
Server headers, decoded payload, and validation decisions.

Request log

No requests sent yet

Response log

Awaiting first request

Server header (raw)

X-Cashu: eyJhIjoyMSwidSI6InNhdCIsIm0iOlsiaHR0cHM6Ly9taW50Lm1pbmliaXRzLmNhc2gvQml0Y29pbiIsImh0dHBzOi8vbWludC5jb2lub3MuaW8iXSwibnV0MTAiOnsia2luZCI6IlAyUEsiLCJwdWJrZXkiOiIwM2I0Li4uN2U5In19

Decoded on client

Run step 2 to decode X-Cashu

Validation checks

Run until final step to evaluate checks.

Final status

No final status yet

This demo follows NUT-24 expectations: 402 with encoded request, client decode, token retry, then strict server-side checks.

Required amount: 21 satAccepted mints: 2NUT-10 lock checkHeader + token flow