Qtum Eclair Public Testnet Installation Guide

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Quantum Chain (Qtum) officially launched the public test version of Qtum Eclair on July 2, 2019, introducing Lightning Network functionality to the Qtum blockchain. This milestone enables users to create payment channels, conduct real-time transactions, and execute micro-payments with minimal fees—paving the way for scalable blockchain-based digital payments.

Scalability remains one of the most pressing challenges in blockchain technology, especially when aiming to support high-frequency, low-value transactions. While Bitcoin can handle approximately 7 transactions per second (TPS), Qtum’s network currently operates at roughly 10 times that capacity. However, to achieve mass adoption for everyday use cases like buying coffee or paying for digital content, further optimization is essential. The integration of the Lightning Network through Qtum Eclair addresses this need by enabling off-chain transaction processing, reducing congestion on the main chain and significantly lowering transaction costs.

👉 Discover how blockchain scalability is revolutionizing digital payments today.

Understanding Qtum Eclair and the Lightning Network

Qtum Eclair is a Lightning Network implementation adapted from Bitcoin’s Eclair project, customized specifically for the Qtum blockchain. It allows two parties to open a bidirectional payment channel on-chain, then conduct unlimited instant transactions off-chain without waiting for block confirmations or incurring high fees.

These off-chain transactions are secured via smart contracts and only settled on the blockchain when the channel is closed. By linking multiple channels together, users can transfer value across the network efficiently and securely—without relying on centralized intermediaries.

This architecture makes Qtum Eclair ideal for:

Core Keywords

Step-by-Step: Installing and Running Qtum Eclair

1. Set Up Qtum Core Wallet

To run Qtum Eclair, you must first install and fully sync a non-pruned, segwit-enabled Qtum Core wallet with ZeroMQ and transaction indexing enabled.

Download Qtum Core

Visit the official GitHub repository to download the latest release compatible with your operating system:
https://github.com/qtumproject/qtum/releases

Configure qtum.conf

Create a configuration file named qtum.conf with the following settings:

server=1
rpcuser=your_secure_username
rpcpassword=your_secure_password
txindex=1
addresstype=bech32
zmqpubrawblock=tcp://127.0.0.1:29000
zmqpubrawtx=tcp://127.0.0.1:29000
🔐 Security Tip: Replace your_secure_username and your_secure_password with strong, unique credentials.

File Locations by OS:

Launch Qtum Core and wait for full blockchain synchronization. Once synced, request testnet QTUM from the faucet:
http://testnet-faucet.qtum.info/

👉 Learn how testnet environments accelerate blockchain innovation.

2. Install Java and Maven

Qtum Eclair is built using Scala, requiring Java Development Kit (JDK) 11+ and Apache Maven.

Install JDK

Install Maven

Download from maven.apache.org or use package managers:

3. Compile Qtum Eclair

Clone the repository and compile the project:

git clone https://github.com/qtumproject/lightning-demo.git
cd lightning-demo
mvn install -DskipTests

After successful compilation, proceed to configure and launch the node.

4. Configure eclair.conf

Create the file ~/.qtum-eclair/eclair.conf with the following content:

eclair {
  chain = "testnet"
  server {
    binding-ip = "0.0.0.0"
    port = 9735
  }
  api {
    enabled = false
    binding-ip = "127.0.0.1"
    port = 8080
    password = "qtum-eclair"
  }
  bitcoind {
    host = "localhost"
    rpcport = 13889
    rpcuser = "your_secure_username"
    rpcpassword = "your_secure_password"
    zmqblock = "tcp://127.0.0.1:29000"
    zmqtx = "tcp://127.0.0.1:29000"
  }
  node-alias = "qtum-eclair"
  node-color = "49daaa"
  min-funding-satoshis = 1000000  # Minimum 0.01 QTUM to open a channel
  max-htlc-value-in-flight-msat = 500000000000  # Up to 5 QTUM
}

Ensure that:

Start the client:

java -jar ./eclair-node-gui/target/lightning-capsule.jar

Using Qtum Eclair: Open Channels & Make Payments

Open a Payment Channel

  1. Right-click the bottom-left corner of the GUI and select "Copy URI" to get your node address.
  2. Click "Channel" > "Open Channel".
  3. Paste your peer's URI and set funding amount (e.g., 10 QTUM).
  4. Confirm; wait for 6 block confirmations before the channel becomes active.

Send and Receive Micro-Payments

Receive Funds:

Send Funds:

Transactions settle instantly with no miner fees.

Close a Channel

When done, click "Close" to finalize the channel. Balances are automatically returned to your Qtum Core wallet after on-chain settlement.

Deploy Qtum Eclair with Docker (Server Setup)

For developers or operators deploying nodes on servers, Docker offers a streamlined setup.

# Pull image and create directories
sudo docker pull qtum/qtum:latest
mkdir /opt/qtum

# Create qtum.conf with Docker-compatible ZMQ settings
echo 'server=1 rpcallowip=172.17.0.0/24 rpcbind=0.0.0.0 rpcuser=foo rpcpassword=bar txindex=1 addresstype=bech32 zmqpubrawblock=tcp://0.0.0.0:29000 zmqpubrawtx=tcp://0.0.0.0:29000' > /opt/qtum/qtum.conf

# Run Qtum container
sudo docker run -tid --rm -v "/opt/qtum:/root/.qtum" --name qtum qtum/qtum:latest qtumd --testnet

# Clone and build Eclair
git clone https://github.com/qtumproject/lightning-demo.git && cd lightning-demo
mkdir /opt/qtum-eclair

# Edit eclair.conf — replace localhost with 'qtumhost'
sudo docker build -t qtum-eclair-img .
sudo docker run -ti --rm --name qtum-eclair -v "/opt/qtum-eclair:/data" -p 9735:9735 --link qtum:qtumhost -e "JAVA_OPTS=-Declair.printToConsole" qtum-eclair-img

Public Testnet Nodes for Testing

Connect to these live nodes for real-world testing:

Use these URIs to open channels and experiment with instant micro-transactions.

For detailed documentation, visit:
https://github.com/qtumproject/documents/blob/master/zh/Qtum-Eclair-Guide.md

Frequently Asked Questions (FAQ)

Q: What is Qtum Eclair used for?
A: Qtum Eclair enables fast, low-cost off-chain transactions using the Lightning Network on the Qtum blockchain, ideal for micropayments and high-frequency trading.

Q: Can I use Qtum Eclair on mainnet?
A: Yes, but currently it's recommended for testnet use only until broader stability and community adoption are achieved.

Q: How secure are Lightning Network payments?
A: Payments are cryptographically secured through smart contracts. Funds are never held by third parties—only participants control their balances.

Q: Is there a minimum amount required to open a channel?
A: Yes, the minimum is 1,000,000 satoshis (≈ 0.01 QTUM).

Q: Do I need technical expertise to run a node?
A: Basic command-line knowledge helps, but GUI tools simplify operations for beginners.

Q: Are transaction fees completely eliminated?
A: Off-chain transactions have no miner fees, though small routing fees may apply when sending via intermediate nodes.

The Future of Digital Payments with Qtum Eclair

As digital economies grow, demand for seamless, real-time payment systems intensifies—especially in sectors like retail, gaming, and IoT. With global digital payment markets projected to exceed $100 billion, scalable solutions like Qtum Eclair are becoming foundational infrastructure.

By supporting frictionless micro-transactions and enhancing blockchain throughput, Qtum Eclair brings cryptocurrencies closer to mainstream usability—enabling payments as effortlessly as scanning a QR code at a café.

👉 See how next-gen blockchain networks are shaping the future of finance.