MQTT 3.1.1 / 5.0 · Linux · Windows · macOS
MQTT Deck does the five things a working MQTT client must do — connect, subscribe, watch, publish, and get your existing connections in — without shipping a browser engine's worth of overhead.
MIT licensed · No account · No telemetry
formerly Ember. The first start of 0.2.0 moves your connections, history and passwords across for you — nothing to re-enter, nothing to export.
01 / What it does
Connect, subscribe, watch, publish, import. MQTT Deck does not chart, script, mock a broker or sync a team, because a feature that does not beat what is already there is not a feature. An agent can drive the same five jobs over MCP.
TCP, TLS, WebSocket and secure WebSocket; MQTT 3.1.1 and 5.0. A username and password, your own client ID, keep-alive, clean session and a connect timeout. TLS takes a custom CA or a client certificate and key. Last will, auto-reconnect with backoff and automatic re-subscription belong to the connection, not to a wizard.
One tab per connection, each with its own buffer, filter, subscription state and compose draft. File them into groups you create yourself — Production, Client A, Testing — then drag, right-click or use the row menu. Search reaches into collapsed groups, and deleting a group never deletes a connection.
Direction, timestamp, topic, payload, QoS and retain on a 29px row. Copy the payload, reuse it in the composer, pin the topic or filter to it without leaving the list. Two independent searches — by topic, and by payload, hex for binary. A virtualised grid holds 50,000 messages without slowing the window, and every topic carries a live message rate so a device going quiet is a number falling.
Click a row for a collapsible JSON tree, syntax-coloured text, raw, a hex dump and MQTT 5 properties; binary payloads are decoded in Rust. A diff shows what changed since the previous message on that topic, line by line. The topics view is one row per topic with its latest payload, age and count.
Topic autocomplete from everything you have seen. Payloads as text, JSON, base64 or hex — binary-safe, encoded in Rust. QoS 0/1/2, retain, and MQTT 5 publish properties: user properties, content type, response topic, correlation data, expiry. Publish history recalls any of them in one click, and the payload field resizes by dragging the band above it.
Every filter carries the MQTT 5 options that change what the broker sends: No Local, Retain As Published, Retain Handling and a subscription identifier. They are editable after the fact, shown as badges beside the filter, and refused on a 3.1.1 connection instead of being dropped without a word.
MQTTX exports import without blocking the window, from the usual OS paths or dropped onto it — existing connections are the usual way in. Connections travel as JSON, YAML, XML, CSV or XLSX, one row each, subscriptions and last will included. Every message is appended to a local daily log for seven days and can be replayed read-only.
Full keyboard operation, including the stream itself. Light, dark, or follow the system. Buffers, filters, drafts, groups and the panel size survive a restart unless you clear them. No telemetry, no accounts, no network call you did not ask for.
mqttdeck-mcp exposes the same engine to any MCP client: list connections,
connect, subscribe, publish, read the stream, wait for a message. It is a bridge,
not a second client — what the agent does is what you see in the window. Loopback
only, token in a 0600 file, one switch to turn it off.
Everything a line in the stream carries, at the density the window uses. Data is monospace; status and direction each keep their own colour.
02 / Keyboard
Every primary workflow has a key path, the message stream included. ⌘ replaces Ctrl on macOS.
Shortcuts
03 / Install
Linux is where MQTT Deck is developed, tested and released from. Windows and macOS build from the same source and are expected to work, best-effort.
Package
sudo dpkg -i mqttdeck_0.2.0_amd64.deb
Needs webkit2gtk-4.1, which most current distributions already have. The package is 3.1 MB.
sudo rpm -i mqttdeck-0.2.0-1.x86_64.rpm
Same WebKitGTK requirement as the .deb. Use dnf install if you prefer it to resolve dependencies.
chmod +x mqttdeck_0.2.0_amd64.AppImage ./mqttdeck_0.2.0_amd64.AppImage
About 81 MB, because it bundles WebKitGTK so it runs on any distribution. Prefer the .deb or .rpm when the system already has webkit2gtk-4.1.
git clone https://github.com/alexsofroniev/mqttdeck cd mqttdeck npm install npm run app:build
Rust 1.77+ and Node 22+, plus the Tauri system dependencies for your platform. Bundles land in src-tauri/target/release/bundle.
04 / Local
No telemetry, no accounts, no update pings. MQTT Deck talks to the brokers you point it at and nothing else.
No analytics, no crash reporting, no version check. The binary makes no network request of its own.
Secret Service, Keychain or Credential Manager. If no keyring exists they stay in
connections.json with mode 0600 — and Settings says so.
The daily log is a local file under the data folder, kept seven days. Settings → Data folder shows the exact path.
05 / Agents
MQTT Deck speaks MCP. Point Claude Code, Cursor, Codex or any MCP client at mqttdeck-mcp and the agent works the same engine you do — same sockets, same buffer, same subscriptions.
Setup
claude mcp add mqttdeck -- mqttdeck-mcp
Anyone who can read agent.json can drive the app, so the file is mode 0600 and holds a token regenerated on every start. Settings → Agent access turns the listener off completely.
{
"mcpServers": {
"mqttdeck": { "command": "mqttdeck-mcp" }
}
}
No path, no port, no key: the bridge finds the running window by itself and says so plainly when the app is closed.
Fourteen tools, all of them the same calls the interface makes. Payloads come back as text when they are text and as base64 when they are not.
06 / Credits
MQTT Deck is designed and built by Alex Sofroniev — the interface, the Rust engine, the releases. The source is public, the licence is MIT, and nothing in the product depends on a private service.
Built with
MIT © 2026 Alex Sofroniev Licence text