Definition
Eclair is an implementation of a full Lightning Network node, written in Scala and maintained by ACINQ. It runs on the Java Virtual Machine (JVM) and follows the Lightning specification (the BOLTs). ACINQ uses Eclair to power its own production infrastructure, and the same software is available as open source under the Apache 2.0 license.
Design and intended use
Eclair is built primarily for server-side deployment rather than running on a phone or a low-power single-board computer. The JVM foundation makes it a natural fit for operators who already run Java/Scala infrastructure and want a node implementation that handles routing and channel management at scale. It connects to a Bitcoin Core backend to watch the chain and broadcast on-chain transactions, and it offers a Docker image for containerized deployment.
APIs and integration
Eclair exposes an HTTP JSON API for opening channels, sending payments, and querying node state. The project documentation stresses that this API should never be exposed directly to the public internet, since it controls funds — a reminder that applies to any Lightning node management interface. A plugin system allows operators to extend behavior without modifying the core.
Eclair is one of several specification-compliant node implementations; we describe each neutrally so node runners can choose what matches their environment. ACINQ also builds the mobile-facing side of this stack — see our entries on Phoenix Wallet and LND (Lightning Network Daemon).
In Simple Terms
Eclair is an implementation of a full Lightning Network node, written in Scala and maintained by ACINQ. It runs on the Java Virtual Machine (JVM)…