Privacy and usage counts

I build wifi-heatmapper on my own, and I only keep working on it if people actually use it. Anonymous counts of installs, app starts and measurements tell me that, and honestly keep me motivated. Nothing identifies you, and you can turn it off any time.

Your surveys, floor plans and results stay on your computer. The only thing the app sends on its own is the small usage counts described here. They are on by default. Settings > Usage counts has the switch, why the app counts, and the exact event it sends.

#What is sent

Three events, sent by the app's server (never by the browser page):

Each event carries these properties, and nothing else:

No measured value is ever sent: no signal strength, dBm, speed, noise, network names or addresses. speed_test only says whether speed tests are switched on, so I can see if the iperf3 part is worth working on.

This is a whole Measurement event, exactly as sent:

POST https://plan.danielhnyk.cz/api/event
User-Agent: wifi-heatmapper/0.7.0 (<random install id>)
Content-Type: application/json

{
  "name": "Measurement",
  "url": "app://wifi-heatmapper/measurement",
  "domain": "app.wifi-heatmapper.danielalder.cz",
  "props": {
    "version": "0.7.0",
    "os": "macos",
    "arch": "arm64",
    "runs_as": "desktop",
    "speed_test": "on"
  }
}

Install and App start look the same, without speed_test. Settings > Usage counts in the app shows the event your computer would send, built by the same code that sends it, and when the last one went out.

#What is never sent

• network names (SSIDs) and access point addresses (BSSIDs, MAC addresses);
• IP addresses of anything you entered, such as the speed test server;
• host names, user names, file names, folder paths and floor plans;
• any measured value: signal strength, dBm, channels, speeds;
• error messages and logs;
• the sudo password.

The event is built from the fixed fields above only. Nothing from a survey reaches it, and the tests check that with surveys full of real-looking network names and addresses.

#Where it goes

To my own Plausible Analytics server at plan.danielhnyk.cz (Plausible Community Edition, self-hosted), not to a third-party analytics service.

Plausible counts unique visitors from the IP address and the User-Agent header, mixed with a random salt that changes every day. It stores neither: no IP address is stored, and the daily hash can't be traced back or linked from one day to the next.

The User-Agent the app sends is wifi-heatmapper/<version> (<install id>). The install id is a random UUID made on your computer the first time usage counts are on. It is not derived from anything about you or your computer, it is only ever in that header, and it is not stored by Plausible. All it does is make one install count as one visitor a day. It is not in bug reports either: they only say whether usage counts are on.

The id is kept in usage-counts.json in the app's data folder (see Where is my data?), next to the on/off setting. Turning usage counts off in Settings deletes it.

The request goes straight from your computer to that server, with a short timeout, in the background. Offline, it is dropped silently: the app works the same with or without it.

#How to turn it off

Any one of these:

• In the app: Settings > Usage counts > turn off Send anonymous usage counts. It is saved for this computer (not in your surveys), and the install id is deleted.
• With an environment variable: start the app with WIFI_HEATMAPPER_TELEMETRY=0 (false, off or no work too). For example WIFI_HEATMAPPER_TELEMETRY=0 npm start, or docker run -e WIFI_HEATMAPPER_TELEMETRY=0 ....
• With DO_NOT_TRACK=1, the common convention for command-line tools.

It is also always off, and Settings says why, when:

• the app runs in mock mode (WIFI_HEATMAPPER_MOCK, npm run dev:mock), which includes the end-to-end tests;
• you run the development server (npm run dev), unless you set WIFI_HEATMAPPER_TELEMETRY=1;
• CI is set (automated builds and tests).

When it is off, nothing is sent and no install id is made.

In Docker, keep the data folder on a volume (-v ./datas:/app/data, as in Running from source), or each new container counts as a new install.

#For developers

WIFI_HEATMAPPER_TELEMETRY_URL sends the events to another Plausible server (the base URL, or its /api/event), and WIFI_HEATMAPPER_TELEMETRY_DOMAIN sets the site name. The code is in src/lib/telemetry.ts.

The MCP server sends nothing: it only talks to the app on your computer.