Privacy Policy
Last updated 19 October 2026
MercLight is an app for controlling the lighting of a Mercedes-Benz vehicle you own, over a Bluetooth OBD adapter. This policy describes every category of data the app processes, and what the website at merclight.app collects when you visit it. The two are separate: nothing collected on the website is linked to the app, your vehicle or your purchases.
The app shows no advertising, contains no advertising or attribution SDK, and does not track you across other apps or websites. Its only measurement is of the purchase screen, by RevenueCat, described below. There is no account to sign up for, no email address collected, and no password: the app creates a pseudonymous account for your device automatically. The website uses web analytics; see This website.
One exception, stated plainly: the app sends crash reports to an error-reporting service (Sentry, operated in the United States) so that faults can be found and fixed. This is error reporting, not analytics: it records what broke, never what you do. It is on by default and you can switch it off at any time in Settings › Testing › Send crash reports. Your VIN, your adapter's Bluetooth address and the security values exchanged with your car are removed on your device before a report is sent. Reports carry no screenshot, no picture of the screen you were on, and no record of what you tapped.
What is collected
| What | Why | Where it goes |
|---|---|---|
| A device identifier, and the account linked to it | To issue the credential that authorises your app to request an unlock, and to carry your purchase | Our own server only. The identifier is created on your device and stays the same if you reinstall the app (on Android it is derived from, and scrambled from, the phone's own identifier for this app). The app creates an account for it automatically. The account is pseudonymous: it carries a random ID, not your name or email, but it is linked to that persistent device identifier. Neither is an advertising identifier, and neither is shared with anyone except as described in this table. |
| Your vehicle's VIN | To identify the model so the right lighting profile is used and, if you buy, to attach your purchase to that specific vehicle | Our own server. To decode the model, the app also sends the U.S. National Highway Traffic Safety Administration's public vPIC service a shortened VIN with its serial number removed. Because your phone makes that request directly, NHTSA also receives network information such as your IP address. |
| A security challenge value from the car's control unit | The unlock response is computed on our server, not in the app | Our own server only. |
| Purchase receipts | To verify with Apple or Google that a purchase is genuine | Our own server, RevenueCat (below), and the store that issued the receipt. |
| Purchases, and views of the purchase screen | To process and restore purchases, and to measure how the purchase screen performs | RevenueCat, a purchase-management service in the United States, on our behalf. It receives an account identifier our server issued (a random ID, not your name or email), your store purchase and its transaction, and which version of the purchase screen was shown. No advertising identifier or device identifier is sent to it. |
| Crash reports | To find and fix faults that would otherwise go unreported | Sentry, an error-reporting service in the United States. Errors only: the error, where in the app it happened, the app version, and the device model and OS version. No VIN, no Bluetooth address, no security values and no advertising identifier. These are stripped on your device before sending. No screenshots and no record of what you tapped. On by default; switchable off in Settings. |
| Your connection to our server | To deliver the app's requests to our server and protect it from attacks | Cloudflare, in the United States, carries every connection between the app and our server, so it processes your IP address and keeps short-lived request logs for security. Our server itself does not keep your IP address. |
| App integrity checks | To confirm that requests to our server come from the genuine app on a genuine device, and to protect the server from abuse | On Android, Google Play Integrity: Google tells our server whether the app was installed from Google Play, whether the device passes Google's integrity checks, its recent activity level and its Android version. On iPhone, Apple App Attest: Apple certifies a key the app creates, and our server keeps that key's public part linked to your device registration until you delete your account. No VIN, name or advertising identifier is involved. Our server keeps counts of the results, without identifiers. |
| Notifications | To send the notifications you allow: service notices, and offers only if you turn them on | Firebase Cloud Messaging, a Google service, delivers them; it creates an installation identifier and a notification token for the app (Firebase Installations). On iPhone, Apple's push notification service delivers them the last step. Our server keeps your device's notification token, its platform, its language and the kinds of notification you chose, linked to your device registration. It is removed when you turn notifications off, when you delete your account, or after 270 days without use. |
| Diagnostic logs | Troubleshooting | They stay on your device unless you choose to export or send them. Identifiers are masked before they are written. |
What the app never collects
- Your location. The app requests no location permission on Android 12 and newer, and declares its Bluetooth scan as never used to derive location.
- Your contacts, photos, calendar, microphone, or camera.
- Any advertising identifier.
Who else receives data
From the app, each as described in the table above:
- Cloudflare carries the connection to our server, and stores our encrypted backups (below), which it cannot read.
- RevenueCat processes purchases and records views of the purchase screen on our behalf.
- Sentry receives crash reports, if you leave crash reporting on.
- Google processes Google Play purchases, answers the app integrity checks on Android (Play Integrity), and delivers notifications (Firebase Cloud Messaging).
- Apple processes App Store purchases, answers the app integrity checks on iPhone (App Attest), and delivers notifications on iPhone.
- NHTSA vPIC, a public database run by the U.S. Department of Transportation, decodes a shortened VIN into a model name.
The website's hosting and analytics providers are listed under This website.
Where data is stored
On your device, and on a server we operate. Your device credential is held in the operating system's keystore (Keychain on iOS, Keystore on Android). The app excludes its stored settings from Android's cloud backup, so your saved vehicles do not leave the phone that way.
How long it is kept
Device registrations and purchase records are kept while your installation is in use. An installation our server has not seen for 12 months is removed. If the app has to register again without being able to prove it is the same installation (for example after a reinstall that lost its credential), it is registered as a new installation with a new, empty account. The old registration and its account are left as they are and follow the same rules as any other: removed once our server has not seen them for 12 months, and an account then deleted if it holds no purchase. An account that holds a purchase is kept, so that Restore Purchases can bring the purchase back; you can have it deleted at any time (see Delete account and data). RevenueCat keeps the purchase and purchase-screen records it processes for us for as long as we use its service, under its data processing terms, and deletes them when you delete your account. Crash reports are kept by Sentry for 30 days and then deleted; they carry no identifier, so they cannot be picked out and erased for one person. You can erase everything linked to you at any time; see Delete account and data. Deletion on our server is immediate and cannot be undone; RevenueCat carries out its part shortly afterwards.
Our server keeps encrypted backups of its records, stored with Cloudflare (R2), so it can be recovered after a failure. Each backup is deleted after at most 180 days, so a deleted account can remain in older backups until then; we use them only to recover the server. The server's operational logs are kept for 30 days; they record shortened identifiers, not your full device or account ID.
Children
MercLight is not directed at children and is not intended for anyone under 13.
Your rights
You can obtain a copy of what we hold, correct it, or erase it, by using the in-app deletion described above or by writing to supportmerclight.app; if you no longer have the app, see Delete account and data for what we need to find your account. Website analytics data is not linked to your name or email, so we usually cannot find a particular visitor in it; you can still ask, and you can withdraw consent to Google Analytics at any time as described below. If you are in the European Economic Area, the United Kingdom or Switzerland, you also have the right to complain to your local data protection authority.
This website
This section covers the website at merclight.app only.
Hosting
The website is served by Cloudflare. Like any hosting provider, Cloudflare processes your IP address and browser details to deliver each page, and keeps short-lived request logs for security and abuse prevention.
Analytics
We use web analytics to learn how many people visit, which pages they read and how they found the website, so that we can improve it. We use Cloudflare Web Analytics, Google Analytics, or both. We never use analytics data for advertising, never sell it, and never combine it with data from the app.
Cloudflare Web Analytics is provided by Cloudflare, Inc., in the United States. It sets no cookies, stores nothing on your device, and does not use your IP address or browser details to identify or follow you. It records the page you view, the page that sent you, your browser and device type, your country, and how quickly the page loaded. Because it stores nothing on your device and cannot identify you, it runs without asking, on the basis of our legitimate interest in understanding how the website is used.
Google Analytics (Google Analytics 4) is provided by Google LLC, in the United States. It uses cookies to recognise a returning browser. It records the pages you view and for how long, the page that sent you, the buttons and links you use, your browser, device type, screen size and language, and your approximate location (city and country), which Google derives from your IP address. Google Analytics 4 does not log or store IP addresses. We keep Google Signals and every advertising feature switched off, and data retention is set to 14 months, after which Google deletes the visit-level data.
Google Analytics runs only if you agree to it. Whenever we use it, the website asks on your first visit. If you decline, or close the question without answering, Google Analytics does not load and sets no cookies. While it is in use, a Cookie settings link at the bottom of every page lets you change your answer at any time; withdrawing consent stops Google Analytics and removes its cookies. When we do not use Google Analytics, the website asks nothing and sets none of the cookies below.
| Name | Set by | Purpose | Lasts |
|---|---|---|---|
_ga | Google Analytics, only with your consent | Tells one returning browser apart from another | 2 years |
_ga_<ID> | Google Analytics, only with your consent | Keeps track of the current visit | 2 years |
| Your cookie choice | This website, only while Google Analytics is in use | Remembers your answer so you are not asked on every page; stored in your browser, never sent to us | 12 months |
Cloudflare and Google are both certified under the EU-U.S. Data Privacy Framework and its UK and Swiss extensions, which is the basis on which this data is transferred to the United States. You can also block Google Analytics in every website at once with Google's browser add-on, or by blocking cookies in your browser settings.
Changes
If this policy changes materially, the updated date above changes and the new version is published here before it takes effect.