Eclair (French for Lightning) is a Scala implementation of the Lightning Network. It can run with or without a GUI, and a JSON API is also available.
- Keep in mind that it is beta-quality software and don't put too much money in it
- Eclair's JSON API should NOT be accessible from the outside world (similarly to Bitcoin Core API)
Lightning Network Specification Compliance
Please see the latest release note for detailed information on BOLT compliance.
Eclair offers a feature rich HTTP API that enables application developers to easily integrate.
For more information please visit the API documentation website.
eclair.api.use-old-api=true parameter, but it is now deprecated and will soon be removed. The old documentation is still available here.
Configuring Bitcoin Core
Eclair needs a synchronized, segwit-ready, zeromq-enabled, wallet-enabled, non-pruning, tx-indexing Bitcoin Core node.
Eclair will use any BTC it finds in the Bitcoin Core wallet to fund any channels you choose to open. Eclair will return BTC from closed channels to this wallet.
You can configure your Bitcoin Node to use either
p2sh-segwit addresses or
bech32 addresses, Eclair is compatible with both modes.
Run bitcoind with the following minimal
server=1 rpcuser=foo rpcpassword=bar txindex=1 zmqpubrawblock=tcp://127.0.0.1:29000 zmqpubrawtx=tcp://127.0.0.1:29000
Eclair is developed in Scala, a powerful functional language that runs on the JVM, and is packaged as a JAR (Java Archive) file. We provide 2 different packages, which internally use the same core libraries:
- eclair-node, which is a headless application that you can run on servers and desktops, and control from the command line
- eclair-node-gui, which also includes a JavaFX GUI
To run Eclair, you first need to install Java, we recommend that you use OpenJDK 11. Eclair will also run on Oracle JDK 1.8, Oracle JDK 11, and other versions of OpenJDK but we don't recommend using them.
Then download our latest release and depending on whether or not you want a GUI run the following command:
- with GUI:
java -jar eclair-node-gui-<version>-<commit_id>.jar
- without GUI:
java -jar eclair-node-<version>-<commit_id>.jar
Eclair reads its configuration file, and write its logs, to
~/.eclair by default.
To change your node's configuration, create a file named
~/.eclair. Here's an example configuration file:
Here are some of the most common options:
|eclair.chain||Which blockchain to use: regtest, testnet or mainnet||mainnet|
|eclair.server.port||Lightning TCP port||9735|
|eclair.api.enabled||Enable/disable the API||false. By default the API is disabled. If you want to enable it, you must set a password.|
|eclair.api.port||API HTTP port||8080|
|eclair.api.password||API password (BASIC)||"" (must be set if the API is enabled)|
|eclair.bitcoind.rpcuser||Bitcoin Core RPC user||foo|
|eclair.bitcoind.rpcpassword||Bitcoin Core RPC password||bar|
|eclair.bitcoind.zmqblock||Bitcoin Core ZMQ block address||"tcp://127.0.0.1:29000"|
|eclair.bitcoind.zmqtx||Bitcoin Core ZMQ tx address||"tcp://127.0.0.1:29000"|
|eclair.gui.unit||Unit in which amounts are displayed (possible values: msat, sat, bits, mbtc, btc)||btc|
Quotes are not required unless the value contains special characters. Full syntax guide here.
reference.conf for full reference. There are many more options!
Java Environment Variables
Some advanced parameters can be changed with java environment variables. Most users won't need this and can skip this section.
datadir is mandatory if you want to run several instances of eclair on the same machine. You will also have to change ports in
eclair.conf (see above).
|eclair.datadir||Path to the data directory||~/.eclair|
|eclair.headless||Run eclair without a GUI|
|eclair.printToConsole||Log to stdout (in addition to eclair.log)|
For example, to specify a different data directory you would run the following command:
java -Declair.datadir=/tmp/node1 -jar eclair-node-gui-<version>-<commit_id>.jar
logback for logging. To use a different configuration, and override the internal logback.xml, run:
java -Dlogback.configurationFile=/path/to/logback-custom.xml -jar eclair-node-gui-<version>-<commit_id>.jar
The files that you need to backup are located in your data directory. You must backup:
- your seed (
- your channel database (
regtestdepending on which chain you're running on)
Your seed never changes once it has been created, but your channels will change whenever you receive or send payments. Eclair will
create and maintain a snapshot of its database, named
eclair.sqlite.bak, in your data directory, and update it when needed. This file is
always consistent and safe to use even when Eclair is running, and this is what you should backup regularly.
For example you could configure a
cron task for your backup job. Or you could configure an optional notification script to be called by eclair once a new database snapshot has been created, using the following option:
eclair.backup-notify-script = "/absolute/path/to/script.sh"
Make sure that your script is executable and uses an absolute path name for
Note that depending on your filesystem, in your backup process we recommend first moving
eclair.sqlite.bak to some temporary file
before copying that file to your final backup location.
You can use the
JAVA_OPTS environment variable to set arguments to
docker run -ti --rm -e "JAVA_OPTS=-Xmx512m -Declair.api.binding-ip=0.0.0.0 -Declair.node-alias=node-pm -Declair.printToConsole" acinq/eclair
If you want to persist the data directory, you can make the volume to your host with the
-v argument, as the following example:
docker run -ti --rm -v "/path_on_host:/data" -e "JAVA_OPTS=-Declair.printToConsole" acinq/eclair
For advanced usage, Eclair supports plugins written in Scala, Java, or any JVM-compatible language.
A valid plugin is a jar that contains an implementation of the Plugin interface.
Here is how to run Eclair with plugins:
java -jar eclair-node-<version>-<commit_id>.jar <plugin1.jar> <plugin2.jar> <...>
Eclair is configured to run on mainnet by default, but you can still run it on testnet (or regtest): start your Bitcoin Node in
testnet mode (add
bitcoin.conf or start with
-testnet), and change Eclair's chain parameter and Bitcoin RPC port:
You may also want to take advantage of the new configuration sections in
bitcoin.conf to manage parameters that are network specific,
so you can easily run your bitcoin node on both mainnet and testnet. For example you could use:
server=1 txindex=1 [main] rpcuser=<your-mainnet-rpc-user-here> rpcpassword=<your-mainnet-rpc-password-here> zmqpubrawblock=tcp://127.0.0.1:29000 zmqpubrawtx=tcp://127.0.0.1:29000 [test] rpcuser=<your-testnet-rpc-user-here> rpcpassword=<your-testnet-rpc-password-here> zmqpubrawblock=tcp://127.0.0.1:29001 zmqpubrawtx=tcp://127.0.0.1:29001
-  The Bitcoin Lightning Network: Scalable Off-Chain Instant Payments by Joseph Poon and Thaddeus Dryja
-  Reaching The Ground With Lightning by Rusty Russell
-  Lightning Network Explorer - Explore testnet LN nodes you can connect to