SatsAPI — a Bitcoin market intelligence API that uses L402 for pay-per-call access on phoenixd nodes. The idea is simple: you make a request, get a 402 back with a Lightning invoice, pay it, resend with the payment_hash, get your data.
No signup. No monthly plan. No API key to rotate. You pay 2-200 sats depending on the endpoint and that's it.
The endpoints:
/v1/price— BTC price + RSI + MAs (3 rate)/v1/mempool— fees + congestion + last block (2 sats)/v1/signal— 9-factor BUY/SELL/HOLD signal with trade setup (150 sats)/v1/summary— everything above combined, structured for AI agents (200 sats)
The L402 implementation uses phoenixd directly. The flow is:
GET /v1/price → 402 + { invoice, payment_hash } pay invoice GET /v1/price?payment_hash=<hash> → 200 + dataNothing fancy, but it works on mainnet and I've been receiving real payments since I launched it quietly last week.
What I found interesting building this: L402 is genuinely a better auth model for programmatic access than API keys. An AI agent can pay autonomously, there's no credential to leak, and you get natural rate limiting through economics.
Docs: https://satsapi.dev/docs Health endpoint if you want to see it's live: https://satsapi.dev/health