Privacy Policy

Effective date: September 29, 2026 · Applies to the Fin apps for iOS and Android ("Fin", "the App") and finapp websites, operated by Welda LLC ("we", "us").

What changed: Fin now includes Appstack, an ad-attribution service that helps us measure our own advertising (see Section 3), and this policy now also covers the Android app.

The short version: Fin has no app accounts and shows no ads. Your habit entries, streaks, check-ins, reflections, pet name, and motivations stay on your device. They are never sent to us, to our service providers, or to ad platforms, and we never share which habit you are quitting. We advertise Fin on Meta, Google, TikTok, and Apple Ads. To measure those ads, Fin includes Appstack’s attribution SDK, which uses random identifiers and device, app, and network information to match installs to ad clicks, and reports installs, finishing onboarding, starting a purchase, and subscribing (with the price paid) to the ad platform whose ad led to the install. Subscription processing sends purchase information to Apple or Google and to RevenueCat.

1. Data We Do Not Collect

Fin is designed to work without knowing who you are. We do not collect, store, or have access to:

Your name, email address, phone number, or any account credentials (there are no accounts).
The habits you are quitting, your streaks, check-ins, relapse history, reflections, motivations, or pet name. These are stored locally on your device only.
Your precise location, contacts, photos, microphone, camera, or health data. (Our attribution provider may estimate your approximate location, such as your country, from your network connection; see Section 3.)
Your device’s advertising identifier (Apple’s IDFA or Google’s advertising ID). Fin does not show Apple’s tracking permission prompt, so the IDFA is not available to Fin or to the SDKs in it, and the Android app does not request permission to use the Google advertising ID.

2. Data Processed for Purchases

Fin offers auto-renewable subscriptions purchased through Apple’s App Store or Google Play. When you purchase a subscription:

Apple (App Store) or Google (Google Play) processes your payment. We never see your payment details. Their handling of your data is described in their privacy policies.
RevenueCat, Inc. acts as our subscription-management processor. It receives purchase receipt information and a randomly generated, anonymous app-user identifier so your subscription can be validated and restored. For ad measurement (Section 3), RevenueCat also stores with that record the Appstack install ID and details of the ad campaign that led to your install, if any, including the ad platform’s click ID. On iPhone it also records your IP address, your device and OS version, the identifier for vendor (IDFV), and Apple’s ad attribution token. RevenueCat sends your subscription events, such as a first purchase or a renewal with its price and currency, to Appstack. RevenueCat’s privacy practices are described at revenuecat.com/privacy.

Purchase records are retained as long as needed to operate your subscription and to meet legal and accounting obligations.

3. Ad Attribution and Measurement

We advertise Fin on other companies’ platforms: Meta (Facebook and Instagram), Google (including Search and YouTube), TikTok, and Apple Ads. To measure which of our ads lead to installs and subscriptions, and to help these platforms deliver our ads more efficiently, the App includes the software development kit (SDK) of Appstack (appstack.tech), a mobile ad-attribution service. Fin itself still shows no ads.

What Appstack receives from the App. When you open Fin, the Appstack SDK sends Appstack:

Random identifiers: an install ID created by the SDK and, on iPhone, Apple’s identifier for vendor (IDFV); on Android, Google Play’s app set ID and the Play Store install referrer, which says which link or campaign, if any, led to the install.
Technical device, app, and network information, such as operating system and app version, language settings, network and mobile carrier details, and hardware details such as memory and storage capacity. Appstack’s servers also receive your IP address when the App connects to them.
A few in-app events: that the App was installed and opened, that you finished onboarding, that you tapped to buy a subscription, and that you subscribed, including the price and currency.
On iPhone, a token from Apple’s AdServices framework that lets Appstack and RevenueCat ask Apple whether the install came from an Apple Ads campaign. This does not use the advertising identifier (IDFA).

How matching works. When someone taps one of our ads, Appstack’s ad link records information about that click, such as the ad and campaign, the ad platform’s click ID, the time, and device and network information, before sending them on to the App Store or Google Play. When Fin is first opened, Appstack compares the information from the App with recent ad clicks to estimate whether the install came from one of our ads. On Android, the Play Store install referrer can confirm this directly.

What ad platforms receive. If your install is matched to one of our ads on Meta, Google, or TikTok, Appstack reports the install and the in-app events listed above (for a subscription, including the price and currency) to that platform, together with the platform’s own click ID and, where needed for matching, technical details such as IP address and device information. As a result, the platform can learn that a person who tapped one of our ads installed or subscribed to Fin, and it may connect this to an account you have with it. The platforms use this to report on and optimize our campaigns and handle it under their own privacy policies. Installs that were not matched to one of our ads are not reported to these platforms. For Apple Ads, we receive campaign results from Apple through Appstack.

What is never shared. These events never include which habit you are quitting, your streaks, check-ins, relapse history, reflections, moods, motivations, pet name, or anything else you enter in the App. We do not have your name, email address, or phone number, so we cannot share them. We do not sell your habit or health information.

Attribution data is kept only as long as needed to measure our advertising and to meet legal obligations. To request deletion, see Section 7.

4. Data Stored on Your Device

Your habit entries and progress live in local storage on your phone. Deleting the App removes this local data. We cannot recover your progress from our servers because we do not receive it. On iPhone, if you use device backups (e.g. iCloud backup), your Fin data may be included in those backups under Apple’s terms and your iCloud settings. The Android app opts out of Android’s automatic cloud backup. Restoring a subscription restores access to Fin; it does not retrieve habit history from a Fin account or server.

5. Website

Our website is a static site hosted on Vercel. It sets no cookies of ours and runs no analytics of ours. Vercel, as hosting infrastructure, may process standard technical request logs (such as IP addresses) to deliver the site securely; see Vercel’s privacy policy for details.

6. Children

Fin deals with topics such as alcohol, nicotine, and gambling and is not directed at children. You must be at least 18 years old (or the equivalent minimum age in your region as indicated by the App Store or Google Play rating) to use Fin. We do not knowingly collect personal information from children.

7. Your Rights

Your habit history, moods, and reflections are stored on your device. You can view your progress while you have access to the App and remove its local data by deleting the App. Deleting the App does not cancel your subscription, and it does not delete the purchase and attribution records held by RevenueCat and Appstack. To request access to or deletion of those records, email team@welda.ai. Because Fin has no accounts, please include the order ID from your App Store or Google Play receipt if you bought a subscription, so we can find your records; if you never subscribed, we may not be able to link a request to your install. We will work with RevenueCat and Appstack to honor applicable rights under laws such as the GDPR and CCPA/CPRA, including access and deletion requests. Information that Meta, Google, or TikTok already received is held by them; you can manage it with their own privacy settings.

8. Data Security

Your in-app data is protected by your device’s own security (device encryption, passcode, Face ID, or screen lock). Purchase processing and ad attribution use Apple’s or Google’s, RevenueCat’s, and Appstack’s infrastructure over encrypted connections.

9. Changes to This Policy

If we change this policy, we will post the updated version on this page with a new effective date. Material changes will be highlighted in the App or on this site.

10. Contact

Welda LLC
Email: team@welda.ai