A Logi Actions SDK plugin that exposes MX Master 4 haptic feedback via a local HTTPS server and WebSocket API.

Requirements

• Logitech MX Master 4 mouse
• Logi Options+ installed
• Logi Plugin Service running

API Server

The plugin runs an HTTPS server on https://local.jmw.nz:41443/ when loaded.

About local.jmw.nz

local.jmw.nz resolves to 127.0.0.1. The plugin uses this domain to serve HTTPS with a valid SSL certificate instead of self-signed certs that browsers reject. The certificate is automatically downloaded from GitHub, cached locally, and refreshed every 24 hours.

REST API Endpoints

Endpoint	Method	Description
/	GET	Health check with service info and available endpoints
/waveforms	GET	List all 15 available haptic waveforms
/haptic/{waveform}	POST	Trigger a specific haptic waveform

WebSocket API

Endpoint:wss://local.jmw.nz:41443/ws

Keeps a warm connection for theoritically lower latency.

Protocol:

• Send a single byte containing the waveform index (0-14)
• No response is sent back
• Connection stays open for repeated triggers

Available Waveforms

The plugin supports 15 haptic waveforms across different categories:

Waveform	Index	Category
sharp_collision	0	Precision enhancers
sharp_state_change	1	Progress indicators
knock	2	Incoming events
damp_collision	3	Precision enhancers
mad	4	Progress indicators
ringing	5	Incoming events
subtle_collision	6	Precision enhancers
completed	7	Progress indicators
jingle	8	Incoming events
damp_state_change	9	Precision enhancers
firework	10	Progress indicators
happy_alert	11	Progress indicators
wave	12	Progress indicators
angry_alert	13	Progress indicators
square	14	Progress indicators

Example Usage

HTTP REST API

# Health check
curl https://local.jmw.nz:41443/
# List all available waveforms
curl https://local.jmw.nz:41443/waveforms
# Trigger haptic feedback (note: -d '' is required to send Content-Length header)
curl -X POST -d '' https://local.jmw.nz:41443/haptic/sharp_collision
curl -X POST -d '' https://local.jmw.nz:41443/haptic/happy_alert
curl -X POST -d '' https://local.jmw.nz:41443/haptic/completed
# {# "success": true,# "waveform": "completed"# }

Note: POST requests require a Content-Length header. When using curl, include -d '' to send an empty body with the proper header otherwise the request will hang. I have some thoughts about this design choice by the otherwise great NetCoreServer library.

WebSocket API (JavaScript)

// Connect to WebSocketconstws=newWebSocket('wss://local.jmw.nz:41443/ws');ws.onopen=()=>{console.log('Connected to HapticWeb');// Trigger "sharp_collision" (index 0)ws.send(newUint8Array([0]));// Trigger "completed" (index 7)ws.send(newUint8Array([7]));// Trigger "happy_alert" (index 11)ws.send(newUint8Array([11]));};ws.onclose=()=>console.log('Disconnected');ws.onerror=(err)=>console.error('WebSocket error:',err);

Technical Details

Architecture

• Server: NetCoreServer-based HTTPS/WSS
• Port: 41443 (HTTPS only)
• Certificate: Auto-managed from GitHub
• CORS: Enabled, any origin
• Binding:127.0.0.1 only

Certificate Management

• Downloads from the GitHub certs branch on first run
• Cached locally in plugin data directory
• Refreshes every 24 hours
• Warns 14 days before expiry
• Falls back to cache if GitHub is unreachable

Installation

Install from the Logitech Marketplace directly within Logi Options+. You can find plugins in the Haptic Feedback area of your MX Master 4 settings.

Manual Installation

1. Open Logitech Options+ and click on your MX Master 4.
2. In the left sidebar, open the HAPTIC FEEDBACK tab and click on the haptic feedback settings popover.
3. In the new right sidebar, click the INSTALL AND UNINSTALL PLUGINS button.
4. Download the HapticWeb.lplug4 release asset from GitHub Releases and double-click it.
5. This will trigger an installation dialog in Logitech Options+. Press continue.
6. The server starts automatically at https://local.jmw.nz:41443/
7. Test at https://haptics.jmw.nz

Development

Building

# Debug build (auto-reloads in Logi Plugin Service)
dotnet build -c Debug
# Release build
dotnet build -c Release

Packaging & Distribution

# Create plugin package
logiplugintool pack ./bin/Release ./HapticWeb.lplug4
# Install locally
logiplugintool install ./HapticWeb.lplug4
# Uninstall
logiplugintool uninstall HapticWeb

Testing

• Manual testing: Use the demo site at https://haptics.jmw.nz
• CLI testing: Use curl commands shown in Example Usage
• Live reload: Debug builds auto-reload when the plugin is rebuilt

Troubleshooting

Certificate Issues

If you see certificate errors:

1. Check plugin status in Logi Options+ (should show green "Normal")
2. Verify internet connection (initial certificate download requires network)
3. Restart Logi Plugin Service
4. Report an issue with the plugin logs if the problem persists

Port Already in Use

If port 41443 is in use:

1. Stop other services using the port: lsof -ti:41443 | xargs kill -9 (macOS/Linux)
2. Restart Logi Plugin Service

WebSocket Connection Failed

If WebSocket connections fail:

1. Verify the server is running: curl https://local.jmw.nz:41443/
2. Check browser console for errors
3. Ensure you're using wss:// (not ws://)
4. Verify local.jmw.nz resolves to 127.0.0.1: ping local.jmw.nz

MIT License

See LICENSE.md for details.