Feedback
Sign in./start

Site navigation

Theme

Learn

  • Roadmaps

Build

  • Projects
  • Developer Tools

Contribute

  • Open Source Projects
  • Issues
  • Reviews
  • First Contribution
  • BountiesSoon
  • Feedback

Prove

  • Builders

Ecosystem

  • Partners
  • Get Funded↗
  • HackathonsSoon
Sign in./start-building

Become an Open Source Builder. Learn. Build. Contribute. Prove.

Feedback welcome — open a GitHub issue.

Learn

RoadmapsStart Building

Build

ProjectsDeveloper Tools

Contribute

Open Source ProjectsIssuesReviewsFirst ContributionSupportFeedback

Prove

Builders Directory

Account

Sign in

Legal

PrivacyTermsCredits

© 2026 Pull // code MIT · curriculum CC BY-SA 4.0

PrivacyTermsCredits

lesson // lightning

Core Lightning

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

advanced2 weeks

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

./sign-in

On this page

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 LightningCLN pluginc-lightningCLN 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

  1. Explain Core Lightning to a teammate without jargon - what problem does it solve?
  2. What would break in production if you misunderstood Core Lightning?
  3. 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
  1. 01

    Worked mental model

    Re-read the diagrams in this lesson once out loud in plain language. If you cannot explain the flow to a friend without jargon, pause and revisit the Mastering Bitcoin / Mastering Lightning chapters linked in Resources. Chapter references are intentional, not decorative.

  2. 02

    Hands-on habit

    Every protocol idea should be paired with one local experiment. That habit turns reading into builder instinct.

    1. Reproduce the happy path on regtest (or Polar for Lightning)
    2. Break it on purpose (wrong fee, expired invoice, offline peer)
    3. Write down what error you saw and which layer produced it (wallet, node, mempool, peer)
  3. 03

    Glossary check

    Pick three terms from this lesson and define them in one sentence each without opening notes. Weak definitions mean the lesson is not finished yet.

  4. 04

    Resource order

    Use Resources in order: narrative book chapter first, then BIP/BOLT for precision, then implementation docs for commands. Jumping straight to RPC flags without the mental model creates brittle knowledge.

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"

Start with existing plugins

Read maintained plugins before writing your own — patterns around JSON-RPC and notifications save weeks.

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.

further reading

  • docsCLN plugins

review // club

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

More repos and GFIs on /discover and /issues.

progress // sign in

Reading is public. Sign in to mark lessons complete, sync across devices, and unlock your roadmap.

./sign-in-to-track

discussion

Discussion

prevLNDnextLDK

On this page

Press Shift + ? for keyboard shortcuts.

Press R to research on Bitcoin Search.

No questions yet — be the first to ask.