Carto

See what your Zenoh system is doing.

Discover active keys. Inspect messages. Decode payloads. Publish with confidence.

Download · Get started · Documentation · Report an issue

Carto is a visual inspector for Zenoh. It brings live traffic, key expressions, payload decoding, and publishing into one workspace, so debugging takes fewer logs, command-line tools, and temporary scripts.

Use it as a desktop app on Windows, macOS, or Linux, or run it in your browser with Carto’s local web server.

Screenshots show Carto 0.9.0 with generated demo traffic.

Get started

1. Open Carto

Download a desktop build from Releases, or run from source.

Prefer a browser? See the web and Docker guide.

2. Connect your router

Your Zenoh router needs the Remote API plugin (zenoh-plugin-remote-api). Enter its WebSocket address in Carto and click Connect.

For a local router, the default is:

ws://127.0.0.1:10000/

Use the Remote API WebSocket endpoint, rather than the router’s REST address or native Zenoh TCP port.

Need a local router? From this repository, run:

docker compose -f docker/compose.yml up --build

See the router setup guide for details.

3. Choose what to watch

Carto starts a 15-second discovery scan when you connect. Select an observed key to preview its payload, then click Watch key to follow incoming messages.

Already know the key expression? Use Add subscription. For example, robots/** watches matching traffic under robots/.

Discovery shows keys that send traffic during the scan. Quiet or inaccessible keys may not appear. Use Scan again when needed.

Inspect messages

Switch between subscriptions using the tabs above the stream. Select a message to inspect its payload, timestamp, size, and encoding, then drag the divider to give the inspector more room. JSON is formatted and color-highlighted; binary data is available as Base64.

• Filter the stream by key or payload preview.
• Changes compares a message with an earlier message on the same key.
• Pin message keeps a payload as a reference for the current app session.
• Edit & republish opens an editable draft so you can review it before sending.

The live buffer is bounded. Pausing freezes the display while newer samples continue to arrive; older payloads can expire. Pin the evidence you need to keep. Learn about capture limits.

Bring your Protobuf definitions

Load your payload’s .proto file along with its common definitions. You can select multiple files, drag them in, or paste definitions.

1. Open the message-type picker in a discovered payload and choose Add schema files…, or use Settings → Protobuf schemas → Add schemas.
2. Add the payload schema and any shared .proto files it needs.
3. Choose the payload’s top-level message type to preview the decoded fields. Use Watch with decoder to keep that decoder when subscribing.

Shared messages and enums resolve across loaded files automatically. Saved schemas are available the next time you open Carto. A successful decode alone does not prove that the selected type matches the payload.

Publish from the same workspace

Choose a target key, write a payload, and click Send message. Carto supports JSON, Text, Base64, and Protobuf, with JSON validation and a formatting action in the editor toolbar.

Type a target or expand Observed keys to choose one. Each format keeps its own draft, and the editor resizes to fit your work. Send with Ctrl+Enter on Windows/Linux or Cmd+Enter on macOS.

Recent publishes restores a sent message as a draft without sending it again. Options contains custom wire encoding and queryable setup, which lets Carto reply to queries with a payload.

Make it your workspace

Switch between light and dark themes, collapse the sidebar for more room, and save connection profiles. Import or export settings to share your schema setup and connection profiles with teammates.

Run from source

Install Node.js 24 or newer, then:

git clone https://github.com/derek-diaz/Carto.git
cd Carto
npm ci
npm run dev:desktop

The first desktop launch may download Electron. If the runtime is missing, run npm run setup:desktop and try again. You still need a reachable Zenoh Remote API endpoint to inspect live traffic.

Built with Electron, React 19, shadcn/ui Rhea, Base UI, Tailwind CSS, and TanStack. See the development guide for builds, checks, architecture, and packaging.

Documentation

I want to…	Start here
Understand discovery, decoding, and capture limits	Using Carto
Run Carto in a browser or Docker	Web and Docker guide
Start a local Zenoh router	Router setup
Generate demo traffic	Scenario pack
Reproduce high-volume traffic	Load testing
Develop or package Carto	Development guide

License

Apache License 2.0. Contributions and feedback are welcome.

Made in Puerto Rico. 🇵🇷