This NATS client is a cross-platform desktop & web application written in Flutter. The client allows users to easily watch & manage NATS messages.

This application currently supports Windows, Linux, macOS and Web platforms.

• Connect to a single NATS server using either plain (nats://) or WebSocket (ws://) schemes
• TLS connection support with optional custom certificates
• Subscribe to multiple subjects
• Automatic re-connect upon lost connection
• Filter received messages
• Find text in received messages
• Send custom messages
• See message details, such as headers, subject and payload. JSON payloads are automatically formatted and syntax highlighted as well!
• Light and Dark themes
• Most recent connection information & theme are persisted between app runs
• Message view settings
• JetStream support (optional, on by default — toggle it off in Settings if you don't need it):
  • Monitor streams and their consumers, including message/byte counts, retention, and ack/redelivery stats
  • Create, purge, and delete streams; create and delete consumers (push or pull, any ack policy)
  • Browse a stream's messages live, or tail a specific consumer and Ack / Nak / Term individual messages
  • Publish messages with JetStream delivery acknowledgement straight from the regular Send Message dialog

These are generated automatically — see scripts/capture_screenshots.ps1 if you're regenerating them after a UI change.

See the help documentation for more details on how to use the application.

This application is also available via Docker Hub. Please note that running the application in Docker means you're running the web flavor. Only the ws:// scheme is available in the browser as explained in the help documentation. Be sure to enable WebSocket support on your target NATS server if you intend to use the Docker version.

To install and run via Docker:

docker run -d -p 8080:80 --name nats-client nverbeek/nats-client-flutter

You may then access the application in your favorite browser at http://localhost:8080.

This project has two test suites:

• test/ — fast widget and unit tests that don't need a running NATS server (dialogs, form validation, pure logic). Run with:

  flutter test test/
  

• integration_test/ — end-to-end tests that drive the real app against a real, locally-running JetStream-enabled nats-server, covering the core message round trip, the full JetStream stream/consumer lifecycle, and the Live Messages tab's filter/find/row-menu/keyboard-shortcut controls. See AGENTS.md's "Recipe E: Local JetStream Testing" for how to stand up a local server, then run each file individually against it, e.g.:

  flutter test integration_test/live_messages_test.dart -d windows
  

GitHub Actions runs both suites on every push and pull request, and every release build is gated on them passing.

To build NATS Client UI, you must first install Flutter for your platform, and get an editor. I highly recommend Android Studio for building, but VS Code is a great second option.

Both Android Studio and VS Code, when setup properly, will automatically offer devices to run this application on and debug.

To build a release, use the following command for your target platform:

flutter build windows --release
flutter build macos --release
flutter build linux --release
flutter build web --release

Release bundles are produced by GitHub Actions for tagged builds. The workflow publishes desktop and web artifacts for:

• Windows x64 and Windows ARM64 packages
• Linux bundles
• macOS bundles
• Web builds
• Docker images

This makes it straightforward to ship the app across desktop and web targets without manually packaging each build.

To build a docker version of the client, run the following command (from the root of the source code):

docker build -t nats-client-flutter .

I am always looking for suggestions on how to improve the NATS Client UI. If you find any bugs or have an idea for a new feature, please let me know by opening a report in the issue tracker on GitHub.

You may directly contribute your own code by submitting a pull request.

This project is licensed under the MIT License.