Polar
Lightning Network regtest GUI. One-click setup of multi-node LN networks for testing.
Repo: github.com/jamaljsr/polar.
Features
- Multi-node: bitcoind + LND / Core Lightning / Eclair, plus Lightning Terminal (litd) and Tap (Taproot Assets). Polar ships no LDK / LDK Node image (checked against Polar v4.0.0, January 2026).
- GUI: drag-and-drop network builder.
- Channel topology editor: open / close channels visually.
- Payment simulator: send/receive between nodes.
- Balance + fee customization.
- Persisted networks: save/restore.
- Tor optional for testing onion-only setups.
- sim-ln activity (Polar 4.0.0, 6 January 2026): activity rules of source / destination / amount / interval drive continuous payments across the network, via bitcoin-dev-project/sim-ln.
- MCP server (Polar 4.0.0, 6 January 2026): 48 tools exposed to
Claude Code / Cursor / Codex over the
@lightningpolar/mcpstdio server, which talks to Polar's HTTP bridge onlocalhost:37373.
Supported images
Version ranges as shipped in Polar 4.0.0 (docker/nodes.json,
read September 2026):
| Node | Versions |
|---|---|
| LND | 0.16.4 - 0.20.0 (beta tags) |
| Core Lightning | 24.08.1 - 25.12 |
| Eclair | 0.9.0 - 0.13.1 |
| Bitcoin Core | 26.0 - 30.0 |
| Taproot Assets | 0.3.3 - 0.7.0 (alpha tags) |
| Terminal (litd) | 0.14.1 - 0.16.0 (alpha tags) |
nodes.json also carries a compatibility map: LND 0.18.4+ pairs with
bitcoind 30.0, LND 0.18.3 and older with 27.0. Custom images (master
branch, local fork) are added via Polar's custom-nodes flow.
Setup
Download installer (Mac/Win/Linux). Requires Docker.
Create network:
- New network → name + chain (regtest).
- Drag node icons (LND, CLN, etc.) onto canvas.
- Add bitcoind backend.
- Start network.
- Open channels via UI.
- Send payments.
Use cases
- Lightning app development: test against real LND/CLN APIs.
- Multisig coordinator testing across LN-aware impls.
- Demos for tutorials, presentations.
- Education: visualize LN flows.
Compared
| Aspect | Polar | Nigiri | Manual regtest |
|---|---|---|---|
| GUI | yes | no | no |
| Multi-LN-impl | LND / CLN / Eclair (+ litd, tapd) | LND + CLN (+ tapd) | yes |
| Esplora explorer | no | yes | manual |
| Use case | LN focus | Bitcoin focus | Custom |
Nigiri column as of Nigiri v0.5.17 (May 2026): nigiri start --ln
brings up Core Lightning, LND and the Taproot Assets daemon
together, not LND alone. It ships no Eclair image.
Common issues
- Docker required and runs containers; resource-heavy on small machines.
- Port conflicts with existing services.
- Old saved networks may break across Polar versions; export node configs separately for portability.