Polar for Windows is a free, open source desktop app that lets Lightning Network developers spin up one or more local networks on their own computer in a few clicks. It is built for people who write applications that send and receive Lightning payments and need a safe place to test them.
Instead of wiring Bitcoin and Lightning nodes together by hand, you arrange the network in a visual interface, start and stop nodes individually, and mine blocks on demand. Everything runs in regtest mode, so no real funds are involved. The app is licensed under MIT and installs with winget, which keeps setup short for anyone comfortable with a command line.
What Is a Regtest Lightning Network?
Bitcoin has several networks. The main network carries real value, while test networks let developers experiment without financial risk. Regtest, short for regression test mode, is a private network where you decide when blocks are created. There is no waiting for the next block and no need to download a large chain history.
The Lightning Network sits on top of Bitcoin. Users open payment channels with each other and send payments across them, which makes small and fast transfers possible. To test that logic, you need several nodes that can open channels, route payments and close them again.
Polar combines these two ideas. It starts a regtest Bitcoin chain and attaches Lightning nodes to it, so your application can exercise the full payment flow on a machine you control. Because the coins are test coins, a mistake costs you little more than a few minutes of setup.
Who Polar Is For
Polar is aimed first at developers who build Lightning-enabled software, such as wallets, merchant checkout flows, streaming payment apps and tools that automate channel management. If your code opens channels, creates invoices or pays them, you need a predictable place to see what happens.
Consider a merchant plugin that creates an invoice when a customer clicks pay. A developer can run a three-node network in Polar, deposit coins into the payer node, open a channel and confirm that the invoice is paid and the webhook fires. When the test fails, the logs and terminal show where the flow stopped.
Educators and students also find this useful. A classroom can build the same network on every laptop and then walk through how channels, routing and invoices work without touching real funds.
How a Local Network Comes Together
Each Polar network is a collection of nodes that you arrange on a canvas. The app handles the wiring so you do not have to write configuration files for every participant. Docker is what makes this practical on a desktop, because it lets each node run in an isolated environment.
Once the network is running, the workflow resembles operating a small production setup. You can start a node, check its logs, mine a block to confirm an open channel, and then stop the node to simulate a failure. Repeating these steps helps you understand how retries, timeouts and recovery should behave in your software.
A few habits make the experience smoother. Keep Docker running before you open Polar, and stop nodes you are not using so your machine stays responsive during longer test sessions.
Key features
Instant regtest networks
RPC access for your application
Drag-and-drop node management
Channel and invoice workflows
Built-in terminal and streaming logs
On-demand block mining and test coins
Taproot Assets support
Cross-platform availability
Supported coins
Polar covers Bitcoin (BTC) and the Lightning Network, with networks that run in regtest mode. Taproot Assets can be minted, sent and received, and invoices can be created and paid for them. Because everything is local, these networks are meant for testing logic, and the coins you deposit have no market value.
How to install Polar on Windows
PS> winget install jamaljsr.Polar- 1
Install Docker Desktop
Polar needs Docker to create local networks, and on Windows the simplest route is Docker Desktop. Install it from the official Docker website, start it, and wait until it reports that it is running before you open Polar.
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Install Polar with winget
Open PowerShell or Command Prompt and run winget install jamaljsr.Polar. Winget downloads the package and runs the installer, so you do not need to search for files manually.
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Or download the Windows build manually
If you prefer a manual install, download the Windows build only from the official website, which links to the project's GitHub Releases page. Avoid mirrors and download links shared in chat messages.
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Verify the file and launch Polar
If the release page lists a SHA-256 checksum or a signature, compare it with your downloaded file before running the installer. In PowerShell, Get-FileHash can calculate the checksum. Then launch Polar from the Start menu.
System requirements
- Windows, the platform this page covers
- Docker Desktop installed and running before you create a network
How to use Polar
Once Polar and Docker are installed, your first network takes only a few minutes. The steps below walk through a basic test with two Lightning nodes, which is enough to check channel opening and invoice payment.
- Open Polar and create a new network.
- Add a second Lightning node by dragging it onto the canvas.
- Start the network and wait until all nodes show as running.
- Deposit regtest coins into the first node so it can fund a channel.
- Open a channel from the first node to the second node.
- Mine a few blocks manually so the channel is confirmed.
- Create an invoice on the second node and pay it from the first.
- If anything fails, check the streaming logs or open a terminal in the node to run commands directly.
Pros & cons
- Free and open source under the MIT license
- Creates regtest Lightning networks in a few clicks
- Visual node management with drag and drop
- Built-in terminal and live logs for each node
- Supports Taproot Assets testing alongside Bitcoin and Lightning
- Quick to install with winget
- Requires Docker to be installed and running
- Designed for development and testing, not for holding real funds
- Running several nodes at once uses noticeable local resources
- Interpreting results still requires some understanding of Lightning concepts
Is Polar safe?
Polar is open source under the MIT license, so you can inspect the code on GitHub. Download it only from the official website or the project's GitHub Releases page, and avoid copies on unofficial download sites. Where a SHA-256 checksum or signature is published, verify the file before running it.
Polar works with regtest coins that have no market value, so the main risk is a compromised installer rather than lost funds. Never enter a seed phrase on third-party websites, and never share one with anyone, including people offering help with a test setup. Check the latest version on the official website before installing.
- Official source only. Download from github.com/jamaljsr. Ignore ads and lookalike domains.
- Check the SHA-256. Compare the installer hash with the value the developer publishes before running it.
- Never share your seed phrase. No developer, support agent or website — including CryptApps — will ever ask for it.
Alternatives
Polar differs from most Lightning tools because it creates the network rather than managing your money. Zap Desktop and Peach are wallets for everyday payments, and Spark Wallet offers a minimal interface on top of c-lightning. Those are useful when you want to pay or receive, but they do not build a test network for you.
Scaling Lightning is a testing toolkit, closer to Polar in purpose, while RPC GUI tool is a general-purpose aid for developers working with bitcoin and similar applications. Polar's main advantage is its visual canvas, where nodes, channels and logs sit in one place. Zap Desktop is no longer supported, so check its status before relying on it.
Specifications
- Price
- Free
- Type
- Open source
- License
- MIT
- Latest version
- 4.0.0
- Last update
- 18 Oct 2026
- Windows support
- Yes (available via winget)
- Official site
- github.com/jamaljsr
- Source code
- github.com/jamaljsr/polar
- Install command
- winget install jamaljsr.Polar
Frequently asked questions
Yes. Polar is free and open source under the MIT license, so you can use it for personal projects and commercial development alike. No purchase is required to create local Lightning networks, and the license lets you study and modify the source code.
Yes. Polar requires Docker to create its local networks, and on Windows the usual choice is Docker Desktop. Install it first, make sure it is running, and then open Polar. Without Docker, the app cannot build the nodes that make up your test network, so the setup will not progress.
No. Polar creates regtest networks, which are isolated from the Bitcoin mainnet where real value moves. The coins you deposit are test coins used only inside your local setup. For real payments, use a dedicated wallet and keep your own keys secure.
Yes. Polar lets you mint, send and receive Taproot Assets and create and pay invoices for them. This is useful for developers prototyping asset transfers over Lightning before connecting to a live environment. You can debug asset flows alongside standard bitcoin payments in the same local network.
Not in the everyday sense. Polar is a development tool for building and testing Lightning networks on your own computer. It is designed for application developers and testers, so it does not replace a wallet you use for regular payments. For daily use, the alternatives listed on this page are a better fit.
Polar lists Windows, macOS, Linux and Docker as supported platforms. On Windows, you can install it with winget. Because the same app concept applies across systems, developers working on different operating systems can follow similar test setups.
A regtest network is a private Bitcoin test mode where you control when blocks are created. Blocks are mined on demand instead of at the normal pace, so tests finish quickly. Polar uses regtest so that Lightning channels and payments can be tested without real money involved.
Verdict
Polar for Windows is a strong pick if you build or test Lightning Network applications and want a fast, visual way to create regtest networks. It is free, MIT-licensed and quick to install with winget, and it covers the operations most payment code depends on, from channels and invoices to Taproot Assets. It is less suited to daily payments or holding funds. Pair it with Docker Desktop, test your flows thoroughly, and treat it as a lab rather than a wallet.