A scala implementation of the Lightning Network.
pm47 Make `publishTransaction` idempotent (#711)
Bitcoin core returns an error `missing inputs (code: -25)` if the tx that we want to publish has already been published and its output have been spent. When we receive this error, we try to get the tx, in order to know if it is in the blockchain, or if its inputs were spent by another tx.

Note: If the outputs of the tx were still unspent, bitcoin core would return "transaction already in block chain (code: -27)" and this is already handled.
Latest commit 8160e79 Sep 20, 2018


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Eclair (french for Lightning) is a scala implementation of the Lightning Network. It can run with or without a GUI, and a JSON-RPC API is also available.

This software follows the Lightning Network Specifications (BOLTs). Other implementations include c-lightning and lnd.

🚧 Both the BOLTs and Eclair itself are still a work in progress. Expect things to break/change!

🚨 If you intend to run Eclair on mainnet:

  • Keep in mind that it is beta-quality software and don't put too much money in it
  • Eclair's JSON-RPC API should NOT be accessible from the outside world (similarly to Bitcoin Core API)
  • Specific configuration instructions for mainnet are provided below (by default Eclair runs on testnet)

Lightning Network Specification Compliance

Please see the latest release note for detailed information on BOLT compliance.


Eclair Demo


Configuring Bitcoin Core

⚠️ Eclair requires Bitcoin Core 0.16.0 or higher. If you are upgrading an existing wallet, you need to create a new address and send all your funds to that address.

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.

Run bitcoind with the following minimal bitcoin.conf:


Installing Eclair

The released binaries can be downloaded here.


Just use the windows installer, it should create a shortcut on your desktop.

Linux, macOS or manual install on Windows

You need to first install java, more precisely a JRE 1.8.

⚠️ If you are using the OpenJDK JRE, you will need to build OpenJFX yourself, or run the application in headless mode (see below).

Then download the latest fat jar 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

Configuring Eclair

Configuration file

Eclair reads its configuration file, and write its logs, to ~/.eclair by default.

To change your node's configuration, create a file named eclair.conf in ~/.eclair. Here's an example configuration file:


Here are some of the most common options:

name description default value
eclair.chain Which blockchain to use: regtest, testnet or mainnet testnet
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.zmq Bitcoin Core ZMQ address "tcp://"
eclair.gui.unit Unit in which amounts are displayed (possible values: msat, sat, mbtc, btc) btc

Quotes are not required unless the value contains special characters. Full syntax guide here.

→ see 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.

⚠️ Using separate 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).

name description default value
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


Eclair uses 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


method params description
getinfo return basic node information (id, chain hash, current block height)
connect nodeId, host, port open a secure connection to a lightning node
connect uri open a secure connection to a lightning node
open nodeId, fundingSatoshis, pushMsat = 0, feerateSatPerByte = ?, channelFlags = 0x01 open a channel with another lightning node, by default push = 0, feerate for the funding tx targets 6 blocks, and channel is announced
updaterelayfee channelId, feeBaseMsat, feeProportionalMillionths update relay fee for payments going through this channel
peers list existing local peers
channels list existing local channels
channels nodeId list existing local channels opened with a particular nodeId
channel channelId retrieve detailed information about a given channel
channelstats retrieves statistics about channel usage (fees, number and average amount of payments)
allnodes list all known nodes
allchannels list all known channels
allupdates list all channels updates
allupdates nodeId list all channels updates for this nodeId
receive description generate a payment request without a required amount (can be useful for donations)
receive amountMsat, description generate a payment request for a given amount
receive amountMsat, description, expirySeconds generate a payment request for a given amount that expires after given number of seconds
checkinvoice paymentRequest returns node, amount and payment hash in an invoice/paymentRequest
findroute paymentRequest nodeId
send amountMsat, paymentHash, nodeId send a payment to a lightning node
send paymentRequest send a payment to a lightning node using a BOLT11 payment request
send paymentRequest, amountMsat send a payment to a lightning node using a BOLT11 payment request and a custom amount
checkpayment paymentHash returns true if the payment has been received, false otherwise
checkpayment paymentRequest returns true if the payment has been received, false otherwise
close channelId close a channel
close channelId, scriptPubKey close a channel and send the funds to the given scriptPubKey
forceclose channelId force-close a channel by publishing the local commitment tx (careful: this is more expensive than a regular close and will incur a delay before funds are spendable)"
audit list all send/received/relayed payments
audit from, to list send/received/relayed payments in that interval (from <= timestamp < to)
networkfees list all network fees paid to the miners, by transaction
networkfees from, to list network fees paid to the miners, by transaction, in that interval (from <= timestamp < to)
help display available methods


A Dockerfile image is built on each commit on docker hub for running a dockerized eclair-node.

You can use the JAVA_OPTS environment variable to set arguments to eclair-node.

docker run -ti --rm -e "JAVA_OPTS=-Xmx512m -Declair.api.binding-ip= -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

Mainnet usage

Following are the minimum configuration files you need to use for Bitcoin Core and Eclair.

Bitcoin Core configuration


Eclair configuration