Who we are
UNDERGROUND ("the app") is an AI car customization studio for iPhone, developed and published by an independent developer (the "Developer", "we", "us"), not a company. This policy explains what the app collects, why, who processes it on our behalf, and the choices you have. It is written to match how the app actually works; if the app changes, this page changes with it.
What we collect
Photos you choose
When you take a photo, pick one from your library or select a preset car, that image is sent to our servers to generate your build. The original photo and every generated result are stored in your private garage so you can reopen, retry and continue builds later. We only access photos you explicitly choose; the app never scans your library.
Your builds
The parts you selected, any notes you typed, the scene preset you used, favourites, and timestamps. Notes are limited to 1000 characters and are sent to the AI model together with your photo.
An anonymous identifier
On first launch the app creates an anonymous account (a random ID) with Firebase Authentication. There is no e-mail, name, phone number or password. This ID ties your garage, your credit balance and your purchases together and is attached to analytics and crash reports so we can debug problems you hit. If you delete the app, the ID is lost and a new one is created on reinstall.
Purchases and credits
Subscriptions and coin packs are processed by Apple. We receive purchase status and product identifiers through RevenueCat and keep a ledger of your credit balance in our database. We never see your card number or Apple ID e-mail.
Usage analytics
Which screens you open, which parts and presets you pick, whether a build succeeded, how long it took, and whether the app was in the background while it ran. Events carry your anonymous ID and a coarse credit-balance bucket, never your photos or notes.
Crash and diagnostic data
If the app crashes or a build fails, a report with the stack trace, device model, OS version, app version and the last screens you visited is sent to Firebase Crashlytics, keyed by your anonymous ID.
Support e-mails
If you use "Report a bug", the app pre-fills your e-mail draft with the app version, device model and OS version so we can reproduce the issue. You see and control everything before sending.
What we do not collect
- No advertising identifier (IDFA) and no cross-app tracking.
- No contacts, location, microphone or full photo-library access.
- No name, e-mail or phone number unless you e-mail us.
How we use it
- To generate your builds. Your photo, selected reference images and your notes are sent to Google's Gemini image model through our own server. Google processes them to produce the result and, under the Gemini API terms for paid usage, does not use them to train its models.
- To keep your garage. Originals and results are stored so you can come back to them.
- To run credits and purchases. Charging credits per build, refunding a failed one, granting credits when a subscription renews.
- To keep the app working. Crash reports and failure diagnostics.
- To improve the product. Aggregated usage analytics, for example which parts are popular or where builds are abandoned.
- To prevent abuse. Our server verifies your anonymous sign-in and rate-limits generation requests per user.
We do not sell personal data, do not show third-party ads, and do not use your photos for marketing or to train AI models.
Who processes data for us
We use the following providers. Each acts on our instructions and under its own security commitments.
| Provider | What for | Data |
|---|---|---|
| Google Firebase (Authentication, Firestore, Cloud Storage) | Anonymous sign-in, credit ledger and build metadata, photo and result storage | Anonymous ID, builds, photos |
| Google Gemini API | Generating the build image | Your photo, reference images, notes, for the duration of the request |
| Cloudflare Workers | Our server that authenticates requests and forwards them to Gemini | Anonymous ID, request contents in transit, request logs (ID, status, duration) |
| Google Analytics for Firebase | Usage analytics | Anonymous ID, events, device and app version |
| Firebase Crashlytics | Crash and failure reports | Anonymous ID, stack traces, device and app version |
| RevenueCat | Subscription and purchase state | Anonymous ID, purchase receipts and product IDs |
| Apple | Payments, App Store distribution | Handled under Apple's own privacy policy |
These providers may store data on servers outside your country, including in the United States. Where required, transfers rely on standard contractual clauses or equivalent safeguards offered by the provider.
Retention and deletion
- Photos and builds stay in your garage until you delete them. Deleting a build in the app removes its metadata and both images from storage.
- Credit ledger is kept while your anonymous account exists.
- Analytics event data is retained by Google Analytics for up to 14 months; crash reports for 90 days.
- Server logs at our Cloudflare Worker are kept for a short period for security and debugging.
- Files cached on your device (recent car images) are removed when you delete the app.
Because the account is anonymous, deleting the app severs the link between you and the stored data; we cannot identify which garage was yours afterwards. To have your garage, ledger and stored images erased while you still have the app installed, e-mail us from the app's Settings screen (Contact us) so the message includes the information we need, and we will delete everything tied to that ID.
Your rights
Depending on where you live (for example under the GDPR in the EU/UK or the KVKK in Türkiye), you may have the right to access, correct, export or erase your data, to object to or restrict processing, and to complain to a supervisory authority. Contact fayan.developer@gmail.com to exercise these rights. Since we hold no contact details, we will ask you to write from within the app or to provide your anonymous ID so we can locate your data.
Children
The app is not directed at children under 13 (or the minimum age in your country) and we do not knowingly collect data from them. If you believe a child has used the app, contact us and we will delete the related data.
Security
Data travels over TLS. Photos and builds are stored under your anonymous ID with rules that allow access only to that ID. Generation requests are authenticated with a short-lived token issued by Firebase and rate-limited on our server. The AI provider's API key never leaves our server. No system is perfectly secure, and we cannot guarantee absolute security.
Changes to this policy
We may update this policy as the app evolves. The effective date at the top tells you when it last changed. Material changes will be highlighted in the app or on this page.
Contact
UNDERGROUND is operated by its independent developer.
E-mail: fayan.developer@gmail.com