# Eclair

> Lightning Network node implementation

**Wikidata**: [Q122818798](https://www.wikidata.org/wiki/Q122818798)  
**Source**: https://4ort.xyz/entity/eclair

## Summary
Eclair is a free, open-source implementation of the Lightning Network, designed to enable fast and low-cost Bitcoin transactions. Developed under the Apache Software License 2.0, it allows users to run, study, modify, and distribute the software, making it a key tool for decentralized payments.

## Key Facts
- **Implementation of**: Lightning Network (a layer-2 scaling solution for Bitcoin)
- **License**: Apache Software License 2.0 (free software with permissive terms)
- **Latest stable version**: 0.5.1 (released on March 3, 2021)
- **Programming language**: Scala (as indicated by Wikidata)
- **Source code repository**: Hosted on GitHub at [ACINQ/eclair](https://github.com/ACINQ/eclair)
- **Stack Exchange tag**: [eclair](https://bitcoin.stackexchange.com/tags/eclair) (used for community discussions)
- **Copyright status**: Copyrighted (as per structured properties)
- **Instance of**: Free software (distributed under terms allowing modification and redistribution)

## FAQs
### Q: What is Eclair, and how does it work?
A: Eclair is a free, open-source implementation of the Lightning Network, a layer-2 protocol that enables fast, low-cost Bitcoin transactions. It allows users to create payment channels, facilitating near-instantaneous transfers while reducing blockchain congestion.

### Q: Who developed Eclair, and where can I find its source code?
A: Eclair was developed by ACINQ, and its source code is available on GitHub at [ACINQ/eclair](https://github.com/ACINQ/eclair). The project is licensed under the Apache Software License 2.0.

### Q: What programming language is Eclair written in?
A: Eclair is primarily written in Scala, as indicated by its Wikidata entry.

### Q: How do I contribute to Eclair?
A: Contributions to Eclair can be made through its GitHub repository. The project welcomes modifications and improvements under its open-source license.

### Q: Is Eclair still actively maintained?
A: Yes, Eclair has been updated with releases as recent as version 0.5.1 in March 2021, indicating ongoing maintenance and development.

## Why It Matters
Eclair plays a crucial role in the Bitcoin ecosystem by providing a robust, open-source implementation of the Lightning Network. As a free software project, it empowers developers and users to customize and deploy their own Lightning Network nodes, fostering decentralization and innovation. By enabling off-chain transactions, Eclair helps address Bitcoin’s scalability challenges, making microtransactions feasible and reducing the need for on-chain congestion. Its permissive license encourages collaboration, allowing other projects to build upon its foundation. Additionally, Eclair’s active development and community engagement ensure its relevance in the evolving landscape of decentralized finance and blockchain technology.

## Notable For
- **Open-source Lightning Network implementation**: One of the earliest and most widely used free software solutions for the Lightning Network.
- **Permissive licensing**: Apache Software License 2.0 allows extensive modification and redistribution, making it a flexible tool for developers.
- **Active development**: Regular updates, including the latest stable release (0.5.1) in 2021, demonstrate ongoing maintenance and community support.
- **Community-driven**: Hosted on GitHub with a dedicated Stack Exchange tag, facilitating collaboration and troubleshooting.
- **Scalability focus**: Enables fast, low-cost Bitcoin transactions, addressing a key limitation of the base Bitcoin protocol.

## Body
### Overview
Eclair is a free and open-source implementation of the Lightning Network, designed to facilitate scalable and low-cost Bitcoin transactions. Released under the Apache Software License 2.0, it allows users to run, study, modify, and distribute the software, aligning with the principles of free software.

### Development and Releases
Eclair has undergone multiple stable releases, with the latest version being 0.5.1, released on March 3, 2021. Previous versions include 0.4.2 (October 19, 2020), 0.4 (July 15, 2020), and earlier iterations in the 0.3 series. Each release is documented on the project’s GitHub repository, providing transparency and accessibility to users.

### Technical Details
Eclair is primarily written in Scala, as indicated by its Wikidata entry. The project is hosted on GitHub, where developers can access the source code and contribute to its development. The software is designed to work within the Lightning Network, a layer-2 protocol that enables off-chain transactions, thereby improving Bitcoin’s scalability.

### Community and Support
Eclair benefits from an active community, as evidenced by its presence on Stack Exchange, where users can discuss and troubleshoot issues related to the software. The project’s open-source nature encourages collaboration, allowing developers to customize and extend its functionality.

### Significance
Eclair’s role in the Bitcoin ecosystem is significant due to its contribution to the Lightning Network’s growth. By providing a free and open-source solution, it democratizes access to scalable Bitcoin transactions, fostering innovation and decentralization. Its permissive license and active development ensure its relevance in the evolving blockchain landscape.

## References

1. [Release 0.3. 2019](https://github.com/ACINQ/eclair/releases/tag/v0.3)
2. [Release 0.3.1. 2019](https://github.com/ACINQ/eclair/releases/tag/v0.3.1)
3. [Release 0.3.2. 2019](https://github.com/ACINQ/eclair/releases/tag/v0.3.2)
4. [Release 0.3.3. 2020](https://github.com/ACINQ/eclair/releases/tag/v0.3.3)
5. [Release 0.3.4. 2020](https://github.com/ACINQ/eclair/releases/tag/v0.3.4)
6. [Release 0.4. 2020](https://github.com/ACINQ/eclair/releases/tag/v0.4)
7. [Release 0.4.1. 2020](https://github.com/ACINQ/eclair/releases/tag/v0.4.1)
8. [Release 0.4.2. 2020](https://github.com/ACINQ/eclair/releases/tag/v0.4.2)
9. [Release 0.5.0. 2020](https://github.com/ACINQ/eclair/releases/tag/v0.5.0)
10. [Release 0.5.1. 2021](https://github.com/ACINQ/eclair/releases/tag/v0.5.1)
11. [Release 0.6.0. 2021](https://github.com/ACINQ/eclair/releases/tag/v0.6.0)
12. [Release 0.6.1. 2021](https://github.com/ACINQ/eclair/releases/tag/v0.6.1)
13. [Release 0.6.2. 2021](https://github.com/ACINQ/eclair/releases/tag/v0.6.2)
14. [Release 0.7.0. 2022](https://github.com/ACINQ/eclair/releases/tag/v0.7.0)
15. [Release 0.8.0. 2022](https://github.com/ACINQ/eclair/releases/tag/v0.8.0)
16. [Release 0.9.0. 2023](https://github.com/ACINQ/eclair/releases/tag/v0.9.0)
17. [Release 0.10.0. 2024](https://github.com/ACINQ/eclair/releases/tag/v0.10.0)
18. [Release 0.11.0. 2024](https://github.com/ACINQ/eclair/releases/tag/v0.11.0)
19. [Release 0.12.0. 2025](https://github.com/ACINQ/eclair/releases/tag/v0.12.0)
20. [Release 0.13.0. 2025](https://github.com/ACINQ/eclair/releases/tag/v0.13.0)
21. [Release 0.13.1. 2025](https://github.com/ACINQ/eclair/releases/tag/v0.13.1)