diff --git a/.github/workflows/PR_build.yml b/.github/workflows/PR_build.yml
index 5e6a005ae..4bb9f0c14 100644
--- a/.github/workflows/PR_build.yml
+++ b/.github/workflows/PR_build.yml
@@ -160,3 +160,38 @@ jobs:
       with:
         name: python-package
         path: python/dist/*
+
+  nodejs:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        submodules: recursive
+    - name: Set up Node.js
+      uses: actions/setup-node@v4
+      with:
+        node-version: '20'
+    - name: Set up Emscripten
+      uses: mymindstorm/setup-emsdk@v14
+      with:
+        version: 3.1.61
+        actions-cache-folder: emsdk-cache
+    - name: Build WebAssembly module
+      working-directory: nodejs/theengs-decoder
+      run: |
+        npm install --ignore-scripts
+        npm run build
+    - name: Run base package tests
+      working-directory: nodejs/theengs-decoder
+      run: npm test
+    - name: Run Node-RED wrapper tests
+      working-directory: nodejs/node-red-contrib-theengs-decoder
+      run: |
+        # The wrapper's only dependency is the locally-built base package,
+        # which isn't on npm yet at PR time, so install it directly.
+        npm install --no-save ../theengs-decoder
+        npm test
+    - uses: actions/upload-artifact@v4
+      with:
+        name: nodejs-wasm
+        path: nodejs/theengs-decoder/dist/*
diff --git a/.github/workflows/publish_npm.yml b/.github/workflows/publish_npm.yml
new file mode 100644
index 000000000..eaf587396
--- /dev/null
+++ b/.github/workflows/publish_npm.yml
@@ -0,0 +1,81 @@
+name: Publish to npm
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'Version to publish (e.g. 2.2.0). Defaults to the release tag.'
+        required: false
+  release:
+    types: [published]
+
+jobs:
+  publish:
+    name: Build and publish Node packages to npm
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        submodules: recursive
+        fetch-depth: 0
+
+    - name: Set up Node.js
+      uses: actions/setup-node@v4
+      with:
+        node-version: '20'
+        registry-url: 'https://registry.npmjs.org'
+
+    - name: Set up Emscripten
+      uses: mymindstorm/setup-emsdk@v14
+      with:
+        version: 3.1.61
+        actions-cache-folder: emsdk-cache
+
+    - name: Resolve publish version
+      id: version
+      env:
+        INPUT_VERSION: ${{ github.event.inputs.version }}
+        REF_NAME: ${{ github.ref_name }}
+      run: |
+        if [ -n "$INPUT_VERSION" ]; then
+          VERSION="$INPUT_VERSION"
+        else
+          VERSION="${REF_NAME#v}"
+        fi
+        echo "Publishing version: $VERSION"
+        echo "version=$VERSION" >> "$GITHUB_OUTPUT"
+
+    - name: Stamp package versions
+      env:
+        VERSION: ${{ steps.version.outputs.version }}
+      run: |
+        cd nodejs/theengs-decoder
+        npm version "$VERSION" --no-git-tag-version --allow-same-version
+        cd ../node-red-contrib-theengs-decoder
+        npm version "$VERSION" --no-git-tag-version --allow-same-version
+        npm pkg set "dependencies.theengs-decoder=$VERSION"
+
+    - name: Build WebAssembly module
+      working-directory: nodejs/theengs-decoder
+      run: |
+        npm install --ignore-scripts
+        npm run build
+
+    - name: Run base package tests
+      working-directory: nodejs/theengs-decoder
+      run: npm test
+
+    - name: Publish theengs-decoder to npm
+      working-directory: nodejs/theengs-decoder
+      env:
+        NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+      run: npm publish --provenance --access public
+
+    - name: Publish node-red-contrib-theengs-decoder to npm
+      working-directory: nodejs/node-red-contrib-theengs-decoder
+      env:
+        NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+      run: npm publish --provenance --access public
diff --git a/CMakeLists.txt b/CMakeLists.txt
index c7c253bd4..2dca99689 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -20,6 +20,27 @@ if(SKBUILD)
     target_compile_features(_decoder PRIVATE cxx_std_11)
     install(TARGETS _decoder LIBRARY DESTINATION TheengsDecoder)
 
+elseif(BUILD_WASM)
+    message(STATUS "Building WebAssembly module via Emscripten")
+
+    add_executable(theengs_decoder_wasm
+        nodejs/theengs-decoder/src/wasm_bindings.cc
+        src/decoder.cpp
+    )
+
+    target_include_directories(theengs_decoder_wasm
+        PRIVATE
+            ${CMAKE_CURRENT_SOURCE_DIR}/src/arduino_json/src
+            ${CMAKE_CURRENT_SOURCE_DIR}/src
+    )
+
+    target_compile_features(theengs_decoder_wasm PRIVATE cxx_std_17)
+
+    set_target_properties(theengs_decoder_wasm PROPERTIES
+        SUFFIX ".js"
+        LINK_FLAGS "-lembind -sMODULARIZE=1 -sEXPORT_NAME=createTheengsDecoderModule -sENVIRONMENT=node -sALLOW_MEMORY_GROWTH=1 -sSINGLE_FILE=1 -sNODEJS_CATCH_EXIT=0 -sNODEJS_CATCH_REJECTION=0"
+    )
+
 else()
 
     add_library(decoder
diff --git a/docs/.vitepress/config.mts b/docs/.vitepress/config.mts
index cc7684e25..540a54db7 100644
--- a/docs/.vitepress/config.mts
+++ b/docs/.vitepress/config.mts
@@ -31,7 +31,9 @@ export default defineConfig({
         items: [
           { text: 'Using the library in a project', link: '/use/include' },
           { text: 'Using with ESP32', link: '/use/ESP32' },
-          { text: 'Using with Python', link: '/use/python' }
+          { text: 'Using with Python', link: '/use/python' },
+          { text: 'Using with Node.js', link: '/use/nodejs' },
+          { text: 'Using with Node-RED', link: '/use/node-red' }
         ]
       },
       {
diff --git a/docs/use/node-red.md b/docs/use/node-red.md
new file mode 100644
index 000000000..f1a0e595b
--- /dev/null
+++ b/docs/use/node-red.md
@@ -0,0 +1,84 @@
+# Using with Node-RED
+
+The `node-red-contrib-theengs-decoder` package adds a **theengs decode**
+node to the Node-RED palette. Wire it after any node that produces BLE
+advertisement messages — for example an MQTT input from a Theengs Gateway,
+or a BLE-scanner node — and it will replace the raw advertisement on
+`msg.payload` with the decoded device information.
+
+The decoder runs as WebAssembly, so installation does not require a C++
+toolchain on the host running Node-RED.
+
+## Installing
+
+From inside Node-RED, open the palette manager (☰ → Manage palette →
+Install) and search for `node-red-contrib-theengs-decoder`. Click
+**Install**.
+
+Or from the command line in your Node-RED user directory (typically
+`~/.node-red`):
+
+```sh
+npm install node-red-contrib-theengs-decoder
+```
+
+Then restart Node-RED.
+
+## Wiring it up
+
+The node accepts `msg.payload` as either an object or a JSON string with
+at least one of:
+
+- `servicedata` — hex string of the BLE service data
+- `manufacturerdata` — hex string of the BLE manufacturer data
+- `id` — device identifier (MAC), optional, used by some decoders
+- `name` — advertised local name, optional, used by some decoders
+
+A typical flow looks like:
+
+```
+[ MQTT in (BTtoMQTT/+) ] → [ theengs decode ] → [ debug ]
+```
+
+When a decoder matches, `msg.payload` becomes an object with `brand`,
+`model`, `model_id`, and any device-specific readings (`tempc`, `hum`,
+`batt`, …).
+
+## Configuration
+
+- **Name** — optional label shown in the editor.
+- **Pass through on no match** — when checked (default), advertisements
+  that no decoder recognizes are forwarded unchanged so the rest of your
+  flow can still see them. When unchecked, unmatched messages are
+  dropped.
+
+## Example flow
+
+The package ships an importable example flow at
+[`examples/decode-flow.json`](https://github.com/theengs/decoder/blob/development/nodejs/node-red-contrib-theengs-decoder/examples/decode-flow.json).
+In Node-RED: ☰ → Import → paste the JSON → **Import**. Deploy, click the
+inject node, and the debug pane should show the decoded miflora reading.
+
+## Building a development version
+
+The Node-RED node depends on the
+[`theengs-decoder`](./nodejs) base package. To work on both from a
+checkout, build the base package locally first:
+
+```sh
+git clone --recursive https://github.com/theengs/decoder.git
+cd decoder/nodejs/theengs-decoder
+npm install
+npm run build
+
+cd ../node-red-contrib-theengs-decoder
+npm install
+npm install --no-save ../theengs-decoder
+```
+
+Then point Node-RED at the local checkout:
+
+```sh
+cd ~/.node-red
+npm install /path/to/decoder/nodejs/node-red-contrib-theengs-decoder
+```
diff --git a/docs/use/nodejs.md b/docs/use/nodejs.md
new file mode 100644
index 000000000..2f852387c
--- /dev/null
+++ b/docs/use/nodejs.md
@@ -0,0 +1,78 @@
+# Using with Node.js
+
+The `theengs-decoder` package is a Node.js binding for the Theengs Decoder
+library. It runs as WebAssembly, so installation does not require a C++
+toolchain on the user's machine.
+
+## Installing from npm
+
+```sh
+npm install theengs-decoder
+```
+
+Requires Node.js 18 or newer.
+
+## Using
+
+```js
+const { decodeBLE, getProperties, getAttribute } = require('theengs-decoder');
+
+const decoded = await decodeBLE({
+  servicedata: '71205d0183d20c6d8d7cc40d08100103',
+});
+// → { brand: 'Xiaomi', model: 'RoPot', model_id: 'HHCCPOT002', moi: 3, mac: 'C4:7C:8D:6D:0C:D2', ... }
+```
+
+If the decoder doesn't recognize the advertisement, `decodeBLE` returns
+`null`. The input may be either an object or a JSON string — both work.
+
+The package also exposes `getProperties(model_id)` and
+`getAttribute(model_id, attribute)`, mirroring the Python binding:
+
+```js
+const props = await getProperties('HHCCPOT002');
+// → { properties: { moi: { unit: '%', name: 'moisture' }, ... } }
+
+const brand = await getAttribute('HHCCPOT002', 'brand');
+// → 'Xiaomi'
+```
+
+These are useful for forwarding decoded values to Home Assistant or other
+automation systems with the right unit and naming metadata.
+
+## Pre-loading the WebAssembly module
+
+The first call to any of the three functions implicitly loads the
+WebAssembly module. To pay that cost at startup instead of on the first
+hot-path call, await `ready()` once:
+
+```js
+const { ready, decodeBLE } = require('theengs-decoder');
+
+await ready();
+// subsequent decodeBLE() calls don't pay the load cost
+```
+
+## Building a development version
+
+Building the module from source requires an
+[Emscripten](https://emscripten.org/) toolchain (`emcc`, `emcmake`,
+`emmake`).
+
+```sh
+git clone --recursive https://github.com/theengs/decoder.git
+cd decoder/nodejs/theengs-decoder
+npm install
+npm run build
+npm test
+```
+
+## Methods
+
+- `ready()` — Resolves once the WebAssembly module is loaded. Optional.
+- `decodeBLE(input)` — Returns the decoded object, or `null` if no
+  decoder matched. Input can be an object or a JSON string.
+- `getProperties(modelId)` — Returns the properties object for a known
+  model id, or `null`.
+- `getAttribute(modelId, attribute)` — Returns the attribute value as a
+  string, or `null`.
diff --git a/nodejs/node-red-contrib-theengs-decoder/.gitignore b/nodejs/node-red-contrib-theengs-decoder/.gitignore
new file mode 100644
index 000000000..504afef81
--- /dev/null
+++ b/nodejs/node-red-contrib-theengs-decoder/.gitignore
@@ -0,0 +1,2 @@
+node_modules/
+package-lock.json
diff --git a/nodejs/node-red-contrib-theengs-decoder/README.md b/nodejs/node-red-contrib-theengs-decoder/README.md
new file mode 100644
index 000000000..e2a166033
--- /dev/null
+++ b/nodejs/node-red-contrib-theengs-decoder/README.md
@@ -0,0 +1,30 @@
+# node-red-contrib-theengs-decoder
+
+A Node-RED node that decodes BLE advertisement messages using
+[Theengs Decoder](https://decoder.theengs.io/).
+
+## Install
+
+From the Node-RED palette manager, search for
+`node-red-contrib-theengs-decoder` and click install. Or, from the
+command line in your Node-RED user directory (typically `~/.node-red`):
+
+```sh
+npm install node-red-contrib-theengs-decoder
+```
+
+The decoder is shipped as WebAssembly — no native toolchain is required.
+
+## Usage
+
+Wire any BLE-scanner node (or an MQTT input from a Theengs Gateway) into
+the **theengs decode** node. The input `msg.payload` should be an object
+with at least one of `servicedata` or `manufacturerdata` (hex string).
+The output `msg.payload` will be the decoded device information.
+
+An importable example flow is included under
+[`examples/`](https://github.com/theengs/decoder/tree/development/nodejs/node-red-contrib-theengs-decoder/examples).
+
+## License
+
+GPL-3.0-only — same as the underlying Theengs Decoder.
diff --git a/nodejs/node-red-contrib-theengs-decoder/examples/decode-flow.json b/nodejs/node-red-contrib-theengs-decoder/examples/decode-flow.json
new file mode 100644
index 000000000..9ce840ba8
--- /dev/null
+++ b/nodejs/node-red-contrib-theengs-decoder/examples/decode-flow.json
@@ -0,0 +1,55 @@
+[
+  {
+    "id": "theengs-example-tab",
+    "type": "tab",
+    "label": "Theengs Decoder",
+    "disabled": false,
+    "info": "Sample flow that injects a Xiaomi RoPot BLE advertisement, decodes it with the theengs-decode node, and prints the result to the debug pane."
+  },
+  {
+    "id": "theengs-example-inject",
+    "type": "inject",
+    "z": "theengs-example-tab",
+    "name": "RoPot sample",
+    "props": [
+      { "p": "payload" }
+    ],
+    "repeat": "",
+    "crontab": "",
+    "once": false,
+    "onceDelay": 0.1,
+    "topic": "",
+    "payload": "{\"servicedata\":\"71205d0183d20c6d8d7cc40d08100103\"}",
+    "payloadType": "json",
+    "x": 160,
+    "y": 120,
+    "wires": [["theengs-example-decode"]]
+  },
+  {
+    "id": "theengs-example-decode",
+    "type": "theengs-decode",
+    "z": "theengs-example-tab",
+    "name": "",
+    "passOnNoMatch": true,
+    "x": 380,
+    "y": 120,
+    "wires": [["theengs-example-debug"]]
+  },
+  {
+    "id": "theengs-example-debug",
+    "type": "debug",
+    "z": "theengs-example-tab",
+    "name": "decoded",
+    "active": true,
+    "tosidebar": true,
+    "console": false,
+    "tostatus": false,
+    "complete": "payload",
+    "targetType": "msg",
+    "statusVal": "",
+    "statusType": "auto",
+    "x": 580,
+    "y": 120,
+    "wires": []
+  }
+]
diff --git a/nodejs/node-red-contrib-theengs-decoder/package.json b/nodejs/node-red-contrib-theengs-decoder/package.json
new file mode 100644
index 000000000..f7a02e939
--- /dev/null
+++ b/nodejs/node-red-contrib-theengs-decoder/package.json
@@ -0,0 +1,46 @@
+{
+  "name": "node-red-contrib-theengs-decoder",
+  "version": "0.1.0",
+  "description": "Node-RED node to decode BLE advertisements using Theengs Decoder.",
+  "keywords": [
+    "node-red",
+    "theengs",
+    "ble",
+    "bluetooth",
+    "decoder",
+    "iot",
+    "home-automation"
+  ],
+  "homepage": "https://decoder.theengs.io/",
+  "bugs": "https://github.com/theengs/decoder/issues",
+  "license": "GPL-3.0-only",
+  "author": "Theengs",
+  "main": "theengs-decode.js",
+  "files": [
+    "theengs-decode.js",
+    "theengs-decode.html",
+    "examples/",
+    "README.md",
+    "LICENSE"
+  ],
+  "scripts": {
+    "test": "node --test test/"
+  },
+  "node-red": {
+    "version": ">=2.0.0",
+    "nodes": {
+      "theengs-decode": "theengs-decode.js"
+    }
+  },
+  "dependencies": {
+    "theengs-decoder": "^0.1.0"
+  },
+  "engines": {
+    "node": ">=18"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/theengs/decoder.git",
+    "directory": "nodejs/node-red-contrib-theengs-decoder"
+  }
+}
diff --git a/nodejs/node-red-contrib-theengs-decoder/test/wrapper.test.js b/nodejs/node-red-contrib-theengs-decoder/test/wrapper.test.js
new file mode 100644
index 000000000..5380c646e
--- /dev/null
+++ b/nodejs/node-red-contrib-theengs-decoder/test/wrapper.test.js
@@ -0,0 +1,91 @@
+'use strict';
+
+const test = require('node:test');
+const assert = require('node:assert');
+const path = require('node:path');
+
+const NODE_FILE = path.resolve(__dirname, '..', 'theengs-decode.js');
+const ROPOT_PAYLOAD = '71205d0183d20c6d8d7cc40d08100103';
+
+function makeMockRED() {
+  const RED = {
+    registered: {},
+    nodes: {
+      createNode(node /*, cfg */) {
+        node._handlers = {};
+        node.error = () => {};
+        node.on = (ev, cb) => {
+          node._handlers[ev] = cb;
+        };
+      },
+      registerType(name, ctor) {
+        RED.registered[name] = ctor;
+      },
+    },
+  };
+  return RED;
+}
+
+async function runOnce(RED, config, payload) {
+  const ctor = RED.registered['theengs-decode'];
+  assert.ok(ctor, 'theengs-decode constructor should be registered');
+  const node = {};
+  ctor.call(node, config);
+  const sent = [];
+  await new Promise((resolve, reject) => {
+    node._handlers.input(
+      { payload },
+      (m) => sent.push(m),
+      (err) => (err ? reject(err) : resolve()),
+    );
+  });
+  return sent;
+}
+
+test('registers the theengs-decode node type', () => {
+  const RED = makeMockRED();
+  require(NODE_FILE)(RED);
+  assert.strictEqual(typeof RED.registered['theengs-decode'], 'function');
+});
+
+test('decodes a matched payload and forwards enriched message', async () => {
+  const RED = makeMockRED();
+  require(NODE_FILE)(RED);
+  const sent = await runOnce(RED, {}, { servicedata: ROPOT_PAYLOAD });
+  assert.strictEqual(sent.length, 1);
+  assert.strictEqual(sent[0].payload.brand, 'Xiaomi');
+  assert.strictEqual(sent[0].payload.model_id, 'HHCCPOT002');
+  assert.strictEqual(sent[0].payload.moi, 3);
+  assert.strictEqual(sent[0].payload.mac, 'C4:7C:8D:6D:0C:D2');
+});
+
+test('passes message through unchanged when no decoder matches (default)', async () => {
+  const RED = makeMockRED();
+  require(NODE_FILE)(RED);
+  const sent = await runOnce(RED, {}, { servicedata: 'deadbeef' });
+  assert.strictEqual(sent.length, 1);
+  assert.deepStrictEqual(sent[0].payload, { servicedata: 'deadbeef' });
+});
+
+test('drops message when passOnNoMatch is false and no decoder matches', async () => {
+  const RED = makeMockRED();
+  require(NODE_FILE)(RED);
+  const sent = await runOnce(
+    RED,
+    { passOnNoMatch: false },
+    { servicedata: 'deadbeef' },
+  );
+  assert.strictEqual(sent.length, 0);
+});
+
+test('accepts a JSON string payload', async () => {
+  const RED = makeMockRED();
+  require(NODE_FILE)(RED);
+  const sent = await runOnce(
+    RED,
+    {},
+    `{"servicedata":"${ROPOT_PAYLOAD}"}`,
+  );
+  assert.strictEqual(sent.length, 1);
+  assert.strictEqual(sent[0].payload.model_id, 'HHCCPOT002');
+});
diff --git a/nodejs/node-red-contrib-theengs-decoder/theengs-decode.html b/nodejs/node-red-contrib-theengs-decoder/theengs-decode.html
new file mode 100644
index 000000000..5efb8235d
--- /dev/null
+++ b/nodejs/node-red-contrib-theengs-decoder/theengs-decode.html
@@ -0,0 +1,64 @@
+<script type="text/javascript">
+  RED.nodes.registerType('theengs-decode', {
+    category: 'function',
+    color: '#3A8FE0',
+    defaults: {
+      name: { value: '' },
+      passOnNoMatch: { value: true }
+    },
+    inputs: 1,
+    outputs: 1,
+    icon: 'font-awesome/fa-bluetooth',
+    label: function () {
+      return this.name || 'theengs decode';
+    },
+    paletteLabel: 'theengs decode'
+  });
+</script>
+
+<script type="text/html" data-template-name="theengs-decode">
+  <div class="form-row">
+    <label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
+    <input type="text" id="node-input-name" placeholder="Name">
+  </div>
+  <div class="form-row">
+    <input type="checkbox" id="node-input-passOnNoMatch"
+           style="display:inline-block; width:auto; vertical-align:top;">
+    <label for="node-input-passOnNoMatch" style="width:auto;">
+      Pass message through unchanged when no decoder matches
+    </label>
+  </div>
+</script>
+
+<script type="text/html" data-help-name="theengs-decode">
+  <p>Decodes BLE advertisement messages using
+     <a href="https://decoder.theengs.io/">Theengs Decoder</a>.</p>
+
+  <h3>Inputs</h3>
+  <dl class="message-properties">
+    <dt>payload <span class="property-type">object | string</span></dt>
+    <dd>A BLE advertisement with at least one of <code>servicedata</code> or
+        <code>manufacturerdata</code> (hex string), and optionally
+        <code>id</code> and <code>name</code>. A JSON string is also accepted.</dd>
+  </dl>
+
+  <h3>Outputs</h3>
+  <dl class="message-properties">
+    <dt>payload <span class="property-type">object</span></dt>
+    <dd>The decoded device information including <code>brand</code>,
+        <code>model</code>, <code>model_id</code>, and any device-specific
+        readings (temperature, humidity, battery, …).</dd>
+  </dl>
+
+  <h3>Configuration</h3>
+  <dl class="message-properties">
+    <dt>Pass through on no match</dt>
+    <dd>When checked (default), messages that no decoder matches are
+        forwarded unchanged so downstream nodes can still see them. When
+        unchecked, unmatched messages are dropped.</dd>
+  </dl>
+
+  <h3>Details</h3>
+  <p>The decoder runs as WebAssembly, so no native build toolchain is
+     required to install this node.</p>
+</script>
diff --git a/nodejs/node-red-contrib-theengs-decoder/theengs-decode.js b/nodejs/node-red-contrib-theengs-decoder/theengs-decode.js
new file mode 100644
index 000000000..1bef94e7e
--- /dev/null
+++ b/nodejs/node-red-contrib-theengs-decoder/theengs-decode.js
@@ -0,0 +1,43 @@
+'use strict';
+
+module.exports = function (RED) {
+  let decoderModule = null;
+
+  function getDecoder() {
+    if (!decoderModule) {
+      decoderModule = require('theengs-decoder');
+    }
+    return decoderModule;
+  }
+
+  function TheengsDecodeNode(config) {
+    RED.nodes.createNode(this, config);
+    const node = this;
+    const passOnNoMatch = config.passOnNoMatch !== false;
+    const decoder = getDecoder();
+
+    decoder.ready().catch((err) => {
+      node.error(`Failed to initialize Theengs Decoder: ${err.message}`);
+    });
+
+    node.on('input', async function (msg, send, done) {
+      send = send || function () { node.send.apply(node, arguments); };
+      done = done || function (err) { if (err) node.error(err, msg); };
+
+      try {
+        const decoded = await decoder.decodeBLE(msg.payload);
+        if (decoded) {
+          msg.payload = decoded;
+          send(msg);
+        } else if (passOnNoMatch) {
+          send(msg);
+        }
+        done();
+      } catch (err) {
+        done(err);
+      }
+    });
+  }
+
+  RED.nodes.registerType('theengs-decode', TheengsDecodeNode);
+};
diff --git a/nodejs/theengs-decoder/.gitignore b/nodejs/theengs-decoder/.gitignore
new file mode 100644
index 000000000..cbdf26b87
--- /dev/null
+++ b/nodejs/theengs-decoder/.gitignore
@@ -0,0 +1,4 @@
+build/
+dist/
+node_modules/
+package-lock.json
diff --git a/nodejs/theengs-decoder/README.md b/nodejs/theengs-decoder/README.md
new file mode 100644
index 000000000..1cbbe443f
--- /dev/null
+++ b/nodejs/theengs-decoder/README.md
@@ -0,0 +1,50 @@
+# theengs-decoder
+
+Node.js binding for [Theengs Decoder](https://decoder.theengs.io/) — decode
+BLE advertisements from a wide range of consumer sensors and devices.
+
+The decoder runs as WebAssembly, so installation does not require a C++
+toolchain on the user's machine.
+
+## Install
+
+```sh
+npm install theengs-decoder
+```
+
+## Usage
+
+```js
+const { decodeBLE, getProperties, getAttribute } = require('theengs-decoder');
+
+const decoded = await decodeBLE({
+  servicedata: '71205d0183d20c6d8d7cc40d08100103',
+});
+// → { brand: 'Xiaomi', model: 'RoPot', model_id: 'HHCCPOT002', moi: 3, mac: 'C4:7C:8D:6D:0C:D2', ... }
+
+const props = await getProperties('HHCCPOT002');
+const brand = await getAttribute('HHCCPOT002', 'brand');
+```
+
+`decodeBLE` accepts either an object or a JSON string and returns the
+decoded device information, or `null` if no decoder matched.
+
+A `ready()` function is also exported; awaiting it pre-loads the WebAssembly
+module so the first hot-path call doesn't pay the load cost.
+
+## Build from source
+
+Requires a working [Emscripten](https://emscripten.org/) toolchain (`emcc`,
+`emcmake`, `emmake`).
+
+```sh
+git clone --recursive https://github.com/theengs/decoder.git
+cd decoder/nodejs/theengs-decoder
+npm install
+npm run build
+npm test
+```
+
+## License
+
+GPL-3.0-only — same as the underlying Theengs Decoder.
diff --git a/nodejs/theengs-decoder/index.d.ts b/nodejs/theengs-decoder/index.d.ts
new file mode 100644
index 000000000..9f9d7a156
--- /dev/null
+++ b/nodejs/theengs-decoder/index.d.ts
@@ -0,0 +1,44 @@
+export interface DecodedBLE {
+  brand?: string;
+  model?: string;
+  model_id?: string;
+  type?: string;
+  [key: string]: unknown;
+}
+
+export interface PropertyInfo {
+  unit?: string;
+  name?: string;
+  [key: string]: unknown;
+}
+
+export interface PropertiesInfo {
+  properties: Record<string, PropertyInfo>;
+}
+
+export type DecodeInput = string | Record<string, unknown>;
+
+/**
+ * Pre-load the WebAssembly module. Optional — the first call to
+ * decodeBLE/getProperties/getAttribute will load it on demand. Calling
+ * ready() at startup avoids paying that cost on the first hot-path call.
+ */
+export function ready(): Promise<void>;
+
+/**
+ * Decode a BLE advertisement object (or JSON string of one). Returns the
+ * decoded device information, or null if no decoder matched.
+ */
+export function decodeBLE(input: DecodeInput): Promise<DecodedBLE | null>;
+
+/**
+ * Look up the property dictionary for a known model_id. Returns null if
+ * the model_id is unknown.
+ */
+export function getProperties(modelId: string): Promise<PropertiesInfo | null>;
+
+/**
+ * Look up a single attribute value for a known model_id. Returns null if
+ * the model_id or attribute is unknown.
+ */
+export function getAttribute(modelId: string, attribute: string): Promise<string | null>;
diff --git a/nodejs/theengs-decoder/index.js b/nodejs/theengs-decoder/index.js
new file mode 100644
index 000000000..8391fe4ae
--- /dev/null
+++ b/nodejs/theengs-decoder/index.js
@@ -0,0 +1,46 @@
+'use strict';
+
+let _modulePromise = null;
+let _decoderInstance = null;
+
+function _loadModule() {
+  if (!_modulePromise) {
+    const createModule = require('./dist/theengs_decoder_wasm.js');
+    _modulePromise = createModule();
+  }
+  return _modulePromise;
+}
+
+async function _getDecoder() {
+  if (_decoderInstance) return _decoderInstance;
+  const Module = await _loadModule();
+  _decoderInstance = new Module.TheengsDecoder();
+  return _decoderInstance;
+}
+
+async function ready() {
+  await _getDecoder();
+}
+
+async function decodeBLE(input) {
+  const decoder = await _getDecoder();
+  const json = typeof input === 'string' ? input : JSON.stringify(input);
+  const out = decoder.decodeBLE(json);
+  if (!out) return null;
+  return JSON.parse(out);
+}
+
+async function getProperties(modelId) {
+  const decoder = await _getDecoder();
+  const out = decoder.getProperties(modelId);
+  if (!out) return null;
+  return JSON.parse(out);
+}
+
+async function getAttribute(modelId, attribute) {
+  const decoder = await _getDecoder();
+  const out = decoder.getAttribute(modelId, attribute);
+  return out || null;
+}
+
+module.exports = { ready, decodeBLE, getProperties, getAttribute };
diff --git a/nodejs/theengs-decoder/package.json b/nodejs/theengs-decoder/package.json
new file mode 100644
index 000000000..a91732b35
--- /dev/null
+++ b/nodejs/theengs-decoder/package.json
@@ -0,0 +1,41 @@
+{
+  "name": "theengs-decoder",
+  "version": "0.1.0",
+  "description": "Decode BLE advertisements from supported sensors and devices using TheengsDecoder, in Node.js via WebAssembly.",
+  "keywords": [
+    "theengs",
+    "ble",
+    "bluetooth",
+    "decoder",
+    "iot",
+    "wasm",
+    "webassembly",
+    "bluetooth-low-energy"
+  ],
+  "homepage": "https://decoder.theengs.io/",
+  "bugs": "https://github.com/theengs/decoder/issues",
+  "license": "GPL-3.0-only",
+  "author": "Theengs",
+  "main": "index.js",
+  "types": "index.d.ts",
+  "files": [
+    "index.js",
+    "index.d.ts",
+    "dist/",
+    "src/",
+    "README.md",
+    "LICENSE"
+  ],
+  "scripts": {
+    "build": "node scripts/build.js",
+    "test": "node --test test/"
+  },
+  "engines": {
+    "node": ">=18"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/theengs/decoder.git",
+    "directory": "nodejs/theengs-decoder"
+  }
+}
diff --git a/nodejs/theengs-decoder/scripts/build.js b/nodejs/theengs-decoder/scripts/build.js
new file mode 100644
index 000000000..f17b74eb4
--- /dev/null
+++ b/nodejs/theengs-decoder/scripts/build.js
@@ -0,0 +1,26 @@
+'use strict';
+
+const { execFileSync } = require('node:child_process');
+const { mkdirSync, copyFileSync } = require('node:fs');
+const path = require('node:path');
+
+const pkgDir = path.resolve(__dirname, '..');
+const repoRoot = path.resolve(pkgDir, '..', '..');
+const buildDir = path.join(pkgDir, 'build');
+const distDir = path.join(pkgDir, 'dist');
+
+mkdirSync(buildDir, { recursive: true });
+mkdirSync(distDir, { recursive: true });
+
+const run = (cmd, args) =>
+  execFileSync(cmd, args, { cwd: buildDir, stdio: 'inherit' });
+
+run('emcmake', ['cmake', '-DBUILD_WASM=ON', repoRoot]);
+run('emmake', ['make', 'theengs_decoder_wasm', '-j']);
+
+copyFileSync(
+  path.join(buildDir, 'theengs_decoder_wasm.js'),
+  path.join(distDir, 'theengs_decoder_wasm.js'),
+);
+
+console.log('Built dist/theengs_decoder_wasm.js');
diff --git a/nodejs/theengs-decoder/src/wasm_bindings.cc b/nodejs/theengs-decoder/src/wasm_bindings.cc
new file mode 100644
index 000000000..063d93d58
--- /dev/null
+++ b/nodejs/theengs-decoder/src/wasm_bindings.cc
@@ -0,0 +1,61 @@
+/*
+    TheengsDecoder - Decode things and devices
+
+    Copyright: (c)Florian ROBERT
+
+    This file is part of TheengsDecoder.
+
+    TheengsDecoder is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    TheengsDecoder is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <emscripten/bind.h>
+#include <string>
+
+#include "decoder.h"
+
+using namespace emscripten;
+
+class TheengsDecoderJS {
+  TheengsDecoder decoder;
+
+ public:
+  TheengsDecoderJS() = default;
+
+  std::string decodeBLE(const std::string& json_data) {
+    StaticJsonDocument<1024> doc;
+    DeserializationError err = deserializeJson(doc, json_data);
+    if (err) return "";
+    JsonObject obj = doc.as<JsonObject>();
+    if (decoder.decodeBLEJson(obj) < 0) return "";
+    std::string buf;
+    serializeJson(obj, buf);
+    return buf;
+  }
+
+  std::string getProperties(const std::string& model_id) {
+    return decoder.getTheengProperties(model_id.c_str());
+  }
+
+  std::string getAttribute(const std::string& model_id, const std::string& attribute) {
+    return decoder.getTheengAttribute(model_id.c_str(), attribute.c_str());
+  }
+};
+
+EMSCRIPTEN_BINDINGS(theengs_decoder_module) {
+  class_<TheengsDecoderJS>("TheengsDecoder")
+      .constructor<>()
+      .function("decodeBLE", &TheengsDecoderJS::decodeBLE)
+      .function("getProperties", &TheengsDecoderJS::getProperties)
+      .function("getAttribute", &TheengsDecoderJS::getAttribute);
+}
diff --git a/nodejs/theengs-decoder/test/decode.test.js b/nodejs/theengs-decoder/test/decode.test.js
new file mode 100644
index 000000000..05e3834e3
--- /dev/null
+++ b/nodejs/theengs-decoder/test/decode.test.js
@@ -0,0 +1,43 @@
+'use strict';
+
+const test = require('node:test');
+const assert = require('node:assert');
+const { ready, decodeBLE, getProperties, getAttribute } = require('..');
+
+const ROPOT_PAYLOAD = '71205d0183d20c6d8d7cc40d08100103';
+
+test('decodes a Xiaomi RoPot servicedata advertisement', async () => {
+  await ready();
+  const result = await decodeBLE({ servicedata: ROPOT_PAYLOAD });
+  assert.ok(result, 'expected a decoded result');
+  assert.strictEqual(result.brand, 'Xiaomi');
+  assert.strictEqual(result.model_id, 'HHCCPOT002');
+  assert.strictEqual(result.moi, 3);
+  assert.strictEqual(result.mac, 'C4:7C:8D:6D:0C:D2');
+});
+
+test('returns null on a payload with no matching decoder', async () => {
+  await ready();
+  const result = await decodeBLE({});
+  assert.strictEqual(result, null);
+});
+
+test('accepts a JSON string as input', async () => {
+  await ready();
+  const result = await decodeBLE(`{"servicedata":"${ROPOT_PAYLOAD}"}`);
+  assert.ok(result);
+  assert.strictEqual(result.model_id, 'HHCCPOT002');
+});
+
+test('getProperties returns the property dictionary for a known model', async () => {
+  await ready();
+  const props = await getProperties('HHCCPOT002');
+  assert.ok(props && props.properties, 'expected a properties object');
+  assert.ok(props.properties.moi, 'expected moisture property');
+});
+
+test('getAttribute returns the brand for a known model', async () => {
+  await ready();
+  const brand = await getAttribute('HHCCPOT002', 'brand');
+  assert.strictEqual(brand, 'Xiaomi');
+});