Core Lightning

Extend CLN with plugins, hooks, and custom RPC commands.

advanced2 weeks

Public lesson — sign in to track progress on this roadmap.

Learning objectives

Operate CLN and use its RPC
Understand plugins and hooks
Know where CLN often leads on protocol features

study // plan

Lessons are primers. Start with Step 1 (required reading) when present, then follow the numbered steps in the article. Depth comes from primary sources, labs, reflection, and evidence.

Research on Bitcoin Search

Core Lightning CLN plugin c-lightning CLN RPC

Step 1 // Required reading

Complete these before the numbered steps in the lesson body. Links are listed here once — not repeated below.

bookMastering the Lightning Network
Ch. 4: Lightning Node Software
docsCore Lightning docs

Reflection prompts

Explain Core Lightning to a teammate without jargon - what problem does it solve?
What would break in production if you misunderstood Core Lightning?
Which BOLT (or implementation doc) is the source of truth for this topic, and what did you verify there?

Lab // CLN RPC + plugin map

Complete Steps 2–3. On Polar/CLN, run getinfo and create an invoice. Skim the plugin docs and list one hook or plugin you would use for a custom feature.

evidence required

getinfo + invoice (or Polar) proof
One plugin/hook you would extend and why
Link to CLN docs or plugin guide section you used

Core Lightning (CLN) emphasizes modularity: a lean daemon extended by plugins. It frequently ships cutting-edge protocol features early.

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

Step 2 — Core idea: daemon + plugins

If you need custom RPC behavior or want to experiment with offers/splicing, CLN’s plugin system is a powerful builder surface.

Loading diagram…

Plugins extend CLN without forking the daemon.

lightning-cli getinfo
lightning-cli invoice 100000 "label" "desc"

Done when: You can contrast CLN’s plugin model with LND’s gRPC app integration style in one sentence.

Step 3 — Try it: RPC + plugin pick (lab)

Run getinfo and mint an invoice on CLN. From the plugin docs, name one hook/plugin for a feature you care about (offers helper, webhook, accounting).

Done when: Lab evidence (RPC proof + plugin pick + source) is complete.

Next lesson

LDK — embed Lightning as a library inside your app.

Review club

Practice on real Lightning OSS changes tied to this chapter. Read the diff, use the checklist, and optionally paste your review comment URL in your lab notes.

CLN plugin example PR
Review a CLN plugin PR for test coverage and hook safety.
pr review
hooksRPC surface
40 min·intermediateopen on GitHub

review checklist

Does the change solve the stated problem?
Are edge cases and rollout behavior covered?
Are tests or test vectors included?
Is the diff minimal and clearly explained?

More repos and GFIs on /discover and /issues.

progress // sign in

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prevLND nextLDK

Step 2 — Core idea: daemon + plugins

If you need custom RPC behavior or want to experiment with offers/splicing, CLN’s plugin system is a powerful builder surface.

Loading diagram…

Plugins extend CLN without forking the daemon.

lightning-cli getinfo
lightning-cli invoice 100000 "label" "desc"

Done when: You can contrast CLN’s plugin model with LND’s gRPC app integration style in one sentence.

Core Lightning

Learning objectives

Step 1 // Required reading

Reflection prompts

Lab // CLN RPC + plugin map

How to study this lesson

Step 2 — Core idea: daemon + plugins

Step 3 — Try it: RPC + plugin pick (lab)

Next lesson

further reading

Review club

Core Lightning

Learning objectives

Step 1 // Required reading

Reflection prompts

Lab // CLN RPC + plugin map

How to study this lesson

Step 2 — Core idea: daemon + plugins

Step 3 — Try it: RPC + plugin pick (lab)

Next lesson

further reading

Review club