Eclair primary sources — 2026-05-02

Project status in this pass

• No canonical standalone whitepaper or litepaper surfaced.
• The clearest current source of truth is the main ACINQ/eclair repository, the public API reference, and the repository docs for guides, architecture, and monitoring.
• The materials consistently frame Eclair as a programmable Lightning node backend tightly coupled to Bitcoin Core for onchain walleting and chain data.

Primary-source snapshots

1) Main repository README

• URL: https://github.com/ACINQ/eclair
• Key excerpt:
  • The README calls Eclair “a Scala implementation of the Lightning Network” and says it follows the Lightning Network Specifications (BOLTs).
  • It says Eclair offers a feature-rich HTTP API for application developers and points operators to in-repo docs for configuration, peer connections, channel opens, sending and receiving payments, and more advanced scenarios.
  • It also states that Eclair relies on Bitcoin Core for blockchain interfacing and onchain funds, does not include an onchain wallet, and requires a synchronized, non-pruning, txindex-enabled Bitcoin Core node.

2) Public API reference

• URL: https://acinq.github.io/eclair/
• Key excerpt:
  • The API reference says Eclair’s API uses HTTP form data and returns JSON-encoded objects or strings, with HTTP Basic auth on every request.
  • The documented endpoints include getinfo, connect, open, rbfopen, cpfpbumpfees, and close, showing that node operations are meant to be driven programmatically.
  • The examples also show detailed channel and fee-management workflows rather than only simple payment APIs.

3) Guides index

• URL: https://raw.githubusercontent.com/ACINQ/eclair/master/docs/Guides.md
• Key excerpt:
  • The guides list advanced topics including custom logging, Bitcoin Core key management, Tor, multipart payments, monitoring, PostgreSQL configuration, circular rebalancing, cluster mode, and architecture.
  • This is a strong clue that Eclair is aimed at operators and integrators managing a serious Lightning backend rather than only hobbyist use.

4) Architecture notes

• URL: https://raw.githubusercontent.com/ACINQ/eclair/master/docs/Architecture.md
• Key excerpt:
  • The architecture doc says Eclair is built in Scala on Akka and explains that the actor model isolates faults, scales across CPUs and machines, and simplifies development and testing.
  • It splits the project into eclair-core, eclair-node, and eclair-front and says eclair-front exists for cluster mode.
  • It further explains that peer connections, channels, and payment attempts are individual actors, which clarifies Eclair’s design as a real node backend with explicit operational architecture.

5) Monitoring docs

• URL: https://raw.githubusercontent.com/ACINQ/eclair/master/docs/Monitoring.md
• Key excerpt:
  • The monitoring guide says Eclair uses Kamon for metrics and spans, supports hosted Kamon APM or self-managed Prometheus export, and ships Grafana dashboards in the repo.
  • Example metrics include local-channel state counts, relayed payments and fees, connected peers, Bitcoin wallet balance, and public-graph metrics.
  • This reinforces that Eclair is meant to be run and observed as production infrastructure.

Working conclusion

Eclair is best cataloged as a Lightning node implementation and operator control plane centered on a programmable HTTP API, actor-based backend architecture, and a tight dependency on Bitcoin Core for onchain walleting. The decisive evidence in this pass was the repeated combination of BOLT-compliant node behavior, explicit operator and clustering docs, and a broad API surface for channel and payment operations.