Programming Lightning: An Introduction to Payment Channels

Programming Lightning is an educational initiative aimed at providing developers and technically inclined individuals with a hands-on understanding of the Lightning network. This project, supported by grants from Spiral and HRF, draws inspiration from "Programming Bitcoin" and strives to teach the inner workings of Lightning through practical coding exercises. Participants are encouraged to fork a GitHub repository to engage with the course materials, which include coding important aspects of the protocol from scratch. The course is designed with an emphasis on practical experience, allowing students to simulate real-world operations such as transaction broadcasting, channel opening, payment sending, and raw transaction decoding.

The instructional content is hosted on Replit, a choice made to facilitate ease of use since each Repl environment comes pre-configured with Bitcoin Core. This setup enables students to effortlessly generate Lightning transactions and engage with the blockchain in a more immediate and impactful way. The resources for this course can be accessed via Replit and the corresponding GitHub repository at GitHub.

Programming Lightning has set forth two principal objectives. Firstly, it aims to provide a rigorous, protocol-level understanding of the Lightning network to empower developers to contribute meaningfully to Lightning's implementations, protocol design, or application development. Secondly, it seeks to offer a technical yet approachable resource for those wishing to gain a comprehensive understanding of Lightning's mechanisms.

Looking ahead, the project plans to expand its curriculum to cover additional facets of Lightning payments, such as authentication, onion routing, gossip, invoices (BOLT 11, BOLT 12), and emerging protocol developments like taproot channels, splicing, and more. This expansion is part of a long-term vision supported by the ongoing Spiral & HRF grant, which extends through 2026. Feedback, corrections, and contributions are encouraged, with open invitations for the community to engage through issues, pull requests, or direct communication at hello@programminglightning.com. This open approach underlines the project's commitment to continuous improvement and inclusivity in fostering a deeper understanding of Lightning across the developer community.