bolt12.cash

A Nostr-first technical demo that resolves a signed Nostr profile, extracts a BOLT12 offer, and exposes a legacy-compatible LNURL / Lightning Address interface.

Nostr = identity kind:0 = profile source BOLT12 = native payment target LNURL = compatibility bridge bitcoind + lightningd backend

What this is

bolt12.cash is a bridge for wallets and clients that still speak LNURL / Lightning Address, while the payment target itself lives in a signed Nostr profile as a raw lno1... BOLT12 offer.

The Nostr profile is the source of truth. The web service does not maintain a custodial account database. It resolves an npub, loads the corresponding kind:0 profile event from relays, extracts lno or bolt12, and serves a Lightning Address-compatible endpoint for older tooling.

Minimal Nostr profile

{
  "name": "Agent 21",
  "about": "Nostr for identity. Bitcoin for value.",
  "lud16": "npub...@bolt12.cash",
  "lno": "lno1...",
  "sp": "sp1..."
}

In this demo, lno and bolt12 are accepted as profile fields.

Current flow

npub@bolt12.cash
↓
GET /.well-known/lnurlp/<npub>
↓
server decodes npub → hex pubkey
↓
server queries Nostr relay for kind:0
↓
profile contains lno / bolt12
↓
LNURL metadata is returned

This part already works in the demo.

Target payment flow

LNURL wallet
↓
GET /api/callback/<npub>?amount=...
↓
server loads BOLT12 offer from Nostr profile
↓
lightningd / Core Lightning fetches invoice from offer
↓
server returns BOLT11 invoice as LNURL response
↓
legacy wallet pays normally

This is the bridge: LNURL input → BOLT12 backend.

Backend architecture

Frontend / API:
- nginx
- FastAPI
- Nostr relay lookup

Bitcoin backend:
- local bitcoind
- pruned node
- self-hosted chain validation

Lightning backend:
- local lightningd / Core Lightning
- BOLT12 offer handling
- fetchinvoice bridge for LNURL clients

Why this design

No DNS payment record dependency
No centralized user database required
Nostr pubkey signs the payment metadata indirectly through the profile
Compatible with old Lightning Address / LNURL wallets
Native BOLT12 can still be exposed directly as raw QR

Live resolver

Paste an npub

Ready. Resolve on demand.

No result yet.

QR: Lightning Address

npub@bolt12.cash

Not generated yet.

QR: LNURL endpoint

Resolve URL

Not generated yet.

QR: Raw BOLT12 offer

lno1...

Resolve first to load the BOLT12 offer.

API surface

GET /                          -> technical demo landing page
GET /health                    -> health check
GET /api/qr?text=...           -> QR code renderer
GET /api/profile/<npub>         -> resolved profile + BOLT12 offer
GET /.well-known/lnurlp/<npub> -> LNURL metadata endpoint
GET /api/callback/<npub>       -> future LNURL → BOLT12 invoice bridge