clightning

c-lightning, commonly referred to as clightning, is an open-source implementation of the Lightning Network protocol written in the C programming language. Developed by Blockstream, it is one of the major reference implementations used to operate Lightning Network nodes. It enables participants to fund channels, route payments, and settle invoices through off-chain transactions.

The project emphasizes a lightweight, modular architecture designed for performance and extensibility. Its core daemon, lightningd, interacts with peers via the Lightning Network protocol and is controlled by a separate command-line client, lightning-cli. A key feature is its plugin system, which allows third-party programs to extend node functionality, such as custom wallets, payment automation, or external accounting.

For blockchain data, c-lightning can be configured to use a Bitcoin Core node or other compatible backends to monitor on-chain events and channel states. It supports dynamic channel management and standard Lightning Network routing features defined by the BOLT specifications, enabling efficient and reliable off-chain payments between peers.

c-lightning is part of the broader ecosystem of Lightning Network implementations, alongside others such as lnd and Eclair. It has been integrated into Blockstream’s products and services and is maintained by an open-source community with ongoing development and contributions hosted on public repositories.