LND

LND is a widely deployed Lightning implementation with gRPC/REST APIs and macaroon-based auth. Many apps integrate here first.

Complete Step 1 // Required reading in the study plan above, then continue here. This opens Implementation.

Step 2 — Core idea: APIs behind macaroons

Production integrations live or die on auth scoping, idempotent payment calls, and careful macaroon storage.

Analogy: Macaroons are VIP wristbands with permissions printed on them. Anyone holding an admin wristband is you — guard them like passwords.

lncli getinfo
lncli addinvoice --amt 1000
lncli payinvoice <bolt11>

Done when: You can name gRPC/REST + macaroon as the integration surface and one auth footgun.

Step 3 — Try it: invoice round-trip (lab)

On Polar LND nodes (or local): getinfo, create invoice, pay from peer. Note TLS + macaroon paths (do not paste secrets into notes).

Done when: Lab evidence (round-trip + macaroon scope sentence + source) is complete.

Next lesson

Core Lightning — plugins, hooks, and a lean daemon model.