Who we are
WattTrue is published by Raghid Ahmad Tawil ("we"). For any question about this policy or about your data, write to apps@raghidtawil.com.
Because WattTrue does not send your data to us, we do not hold any of it. Everything described below stays on devices you own.
The Android app
What it reads
While you run a measurement, the app reads the battery information Android makes available to every app:
- charge level, battery current and voltage, battery temperature and battery health;
- whether a charger is connected and of which kind (cable, wireless or dock), and whether the phone reports that it is charging;
- the charging limits the phone reports having agreed with the charger;
- whether the screen is on or off, and the time of each reading.
When it connects to your computer, it also sends your phone's model name, its Android version and the WattTrue version, once, so the computer can label the run. It does not read your contacts, messages, photos, files, location, accounts or any identifier for advertising.
Where it goes
Readings go to one place: the computer you pair the phone with, shown on that computer's screen as an address and a pairing code. They travel over your own local network (or a USB cable, for developers) and are not sent to WattTrue, to an analytics service or to anyone else.
The connection is a plain WebSocket on your local network and is not encrypted. It carries battery readings and the phone's model name — nothing that identifies you — and the pairing code stops other devices on the network from adding readings to your run. Use it on a network you trust.
What it keeps
The app keeps its own copy of your most recent runs — up to 40 runs or 32 MB, whichever comes first — in its private storage on the phone, so you can look back without a computer. Older runs are removed automatically, and everything is deleted when you uninstall the app. Each saved run also notes the address of the computer it was sent to.
Measuring with the screen off
WattTrue's reason to exist is measuring with the screen off, because a lit display
distorts the reading. To keep measuring after you lock the phone, the app runs a
foreground service of the type dataSync — Android's
category for transferring data to another device, which is what it does: it sends
readings to your computer. Android shows a notification the whole time it runs,
and it runs only while you are measuring. It stops when you stop the measurement or
close the app, and it never restarts on its own.
Android permissions
These are the permissions WattTrue declares, each with the reason it needs it:
| Permission | Why WattTrue needs it |
|---|---|
Network accessandroid. | To send readings to the computer you paired, over your own local network. WattTrue contacts no other address. |
View network connectionsandroid. | Lets the app see whether the phone is connected to a network. It does not reveal which network you are on or where you are. |
Run in the foregroundandroid. | Keeps a measurement running after you lock the screen - the whole point of WattTrue, because a lit screen distorts the reading. Android shows a notification for as long as it runs. |
Foreground service: data syncandroid. | Android 14 and later require the foreground service to declare its type. WattTrue's type is data sync, because it transfers readings to another device - your computer. |
Show notificationsandroid. | For the notification that tells you a measurement is running. If you decline, measuring still works; Android shows the notification silently. |
WattTrue does not request location, camera, microphone, contacts, calendar, SMS or
phone permissions. The connection to your computer is made over plain
ws://, because a computer on your home network has no certificate; the
app is therefore allowed to open unencrypted connections, and uses that only to
reach the computer you paired.
The desktop app
The desktop app listens on your local network (port 8787) for the phone you pair, shows the readings, and — when you choose to record — saves each run as a folder on your computer holding the readings exactly as they arrived and a short description: when it started and ended, the name you gave it, and the phone's model and software versions. Those folders are yours: you can open, copy, share or delete them, and the app shows where they are kept.
The desktop app does not send anything to WattTrue or to anyone else. Connections from your local network are refused unless they present the pairing code the desktop is showing.
iPhone
An iPhone version is in development and is not yet available. iOS gives apps only the battery level in 5 % steps, whether the phone is charging, Low Power Mode and a thermal-pressure level. That is all it would read, and it would send it only to your paired computer, as the Android app does. This policy will be updated before an iPhone version is released.
This website and the run viewer
This website is a set of static pages. It sets no cookies, uses no analytics, shows no ads and loads nothing from any other site — its fonts are served from here, and the pages instruct your browser to refuse any request to another address.
The run viewer opens a saved run inside your browser. The files you choose are read on your computer and are never uploaded; closing the tab discards them.
The site is served by Cloudflare Pages. Like any web host, it may keep ordinary access logs (such as IP addresses and the pages requested) to operate and protect its service. WattTrue does not receive or use those logs.
Your choices
Since WattTrue does not collect your data, there is nothing for us to hand over, correct or delete — your runs are on your own devices, where you control them. To remove everything: delete the run folders on your computer and uninstall the apps.
WattTrue is not directed at children and does not knowingly receive information from anyone, of any age.
Changes to this policy
If what WattTrue handles changes — for example, when the iPhone version is released — this page will be updated before the change ships, and the date at the top will change with it.
Contact
Questions about privacy: apps@raghidtawil.com.