Trailium / Privacy policy
Privacy Policy
Your privacy matters. Trailium processes your photos on your phone and does not upload them, unless you choose to submit one to the Showcase. This policy explains what limited data we do collect (app analytics, ads, referral links and optional Showcase uploads), why, and your rights — including full rights under EU/EEA law.
Last updated: November 2, 2026
Key Points
Your Photos Stay Yours
All processing happens on your device. Photos are uploaded only if you choose to submit one to the Showcase.
No Account Needed
No name, no email, no sign-up. We do collect app analytics under a random app identifier, described in Section 2.
Free with Ads
The app is ad-supported via Google AdMob. EU/EEA users are shown a consent dialog before any personalized ads are served.
Table of Contents
- Data Controller
- Information We Collect
- Advertising & Consent (incl. EU/EEA)
- Legal Basis for Processing (GDPR)
- How We Use Your Information
- Third-Party Services
- International Data Transfers
- Data Retention
- Your Rights
- Additional Rights for EU/EEA Users
- Children's Privacy
- Changes to This Policy
- Contact & Complaints
1. Data Controller
The data controller for the Observin apps (Trailium, Starro, Intervals, Echo and Tankbound) and this website is the individual developer who publishes them on the Google Play Store. For any privacy-related enquiry, please use the contact details in Section 13.
On iPhone and iPad, Trailium is distributed through Apple's App Store under the bundle ID com.observin.trailium, and Apple handles download and purchase data under its own privacy policy. Trailium on iOS requests non-personalized ads only and does not track you across other companies' apps. Photons and referral links are not offered on iOS, so no referral data is sent. Location is used only while you use the app. Where this policy mentions Android settings or the Google Advertising ID, use Settings → Trailium on iOS to manage permissions, and delete the app to remove its data.
This privacy policy applies to the Trailium apps for Android (Google Play Store) and for iPhone and iPad (App Store), and to this informational website. Our other apps have their own, separate policies: Starro edits photos on-device and has its own ads and analytics (Starro Privacy Policy), Intervals uses an accessibility service to tap your camera's shutter and never touches your photos (Intervals Privacy Policy), Echo is a free arrow puzzle with on-device progress and AdMob ads (Echo Privacy Policy), and Tankbound is a free artillery game with on-device progress and optional rewarded ads (Tankbound Privacy Policy).
2. Information We Collect
Device & Technical Information
Trailium reads basic device information (device model, Android version, screen size) to tune image processing for your phone. The same details, plus app version and language, are also sent to our analytics provider with the events described below.
Usage Analytics (PostHog)
We use PostHog to record which screens and features are used, how long processing takes, and when the app crashes or logs an error, so we can fix what breaks and decide what to build next. Events carry a random app-level identifier, not your name. PostHog stores this data on servers in the United States (Section 7).
Session Replays
We record short, screenshot-based replays of app screens to find usability problems. Text you type is masked. Until image masking ships, photos you are working on can appear in a replay.
Photo Library Access
Trailium requests access to your photo library solely to let you import images for processing and to save results to your device. We only access photos you explicitly select. We never scan, browse, upload, or share your photo library. The one exception is a photo you deliberately submit to the Showcase.
Camera, Location & Notifications
The built-in night camera uses the Camera permission. If you open Tonight's Sky, the sky map or the AR overlay, Trailium asks for your location and uses it on your phone to work out what is above you, plus the local light-pollution level. Those coordinates stay on the device and are not sent to us or to PostHog. Long stacking jobs continue in the background with a local notification.
Referral Links & Install Attribution
If you install Trailium through a referral link, Google Play passes the referral code to the app. Trailium sends that code, a random device key and the app name to our referral service on observin.dev so Photons can be credited once per install (Section 6).
Optional Showcase Upload
The Community Showcase is switched off by default. If it is enabled and you choose to submit a photo, that image and the caption you write are uploaded to Cloudinary and shown publicly. Nothing is uploaded unless you press submit.
Advertising Identifiers
Our advertising partner (Google AdMob) may collect your device's advertising identifier (Google Advertising ID / GAID) and certain usage signals to serve ads. For EU/EEA users, this only occurs after you grant consent via our consent management prompt. See Section 3 for details.
Information We Do NOT Collect
- Your name, email address, or any directly identifying information
- Your contacts or calendar
- Your photo library (a single photo leaves your phone only if you submit it to the Showcase)
- Your exact location history (location is used on-device for the sky view and is not transmitted)
3. Advertising & Consent (incl. EU/EEA)
How We Use Advertising
Trailium is free and supported by in-app advertising served through Google AdMob: a rewarded ad you choose to watch for an unlocked export, native ads in the sky list, and an ad slot on the capture screen. Advertising revenue allows us to offer the app at no charge.
EU/EEA Users — Consent Management (GDPR & ePrivacy)
If you are located in the European Union, European Economic Area, or the United Kingdom, we are required by the GDPR and the ePrivacy Directive to obtain your consent before collecting or processing personal data for advertising purposes.
We use the Google User Messaging Platform (UMP), which implements the IAB Transparency & Consent Framework (TCF v2.2), to present a consent dialog when you first open the app. This dialog allows you to:
- Review all ad technology vendors and their data processing purposes
- Accept or decline personalized (interest-based) advertising
- Accept or decline non-personalized advertising
- Manage granular consent for each data processing purpose
If you decline consent, you will still see ads, but they will be non-personalized and no advertising identifier or behavioral data will be collected or used for ad targeting.
Withdrawing or Changing Your Consent
You can change or withdraw your advertising consent at any time from your device settings, as described below. The consent form shown on first launch is not reopened from inside Trailium today.
- Android: Settings → Google → Ads → Delete advertising ID / Opt out of Ads Personalization
Non-EU Users
Outside the EU/EEA/UK, personalized ads may be served based on your advertising ID by default. You can opt out of personalized advertising at any time through your Android device settings (Settings → Google → Ads).
Google AdMob Data Collection
Google AdMob may collect and use the following data, subject to your consent where required:
- Device advertising identifier (GAID)
- IP address (used for approximate geolocation and fraud prevention)
- App usage and interaction data with ads
- Device type, OS version, and language settings
Google's data practices are governed by the Google Privacy Policy and the Google AdMob Privacy & Security guidelines.
4. Legal Basis for Processing (GDPR)
For users in the EU/EEA/UK, we rely on the following legal bases under Article 6 of the GDPR for each processing activity:
| Processing Activity | Legal Basis | Details |
|---|---|---|
| Local image processing | Contract (Art. 6(1)(b)) | Necessary to provide the app's core functionality you requested. |
| App analytics (PostHog) | Legitimate interests (Art. 6(1)(f)) | Improving app quality and stability; events use a random identifier, not your name. |
| Personalized advertising | Consent (Art. 6(1)(a)) | Only processed after you grant consent via the in-app TCF dialog. |
| Non-personalized advertising | Legitimate interests (Art. 6(1)(f)) | Serving contextual ads to fund the free app; no behavioral profiling. |
5. How We Use Your Information
App Improvement
Analytics data helps us understand which features are popular, identify performance bottlenecks, fix crashes, and prioritize development.
Processing Optimization
Device information is used locally to auto-tune processing parameters (thread count, memory allocation) for your specific hardware. Basic device details can also appear in analytics events (Section 2).
Ad Support
Trailium is free and supported by ads. Ad-related data is used by Google AdMob to display advertisements. We do not sell your personal data. We do not build personal profiles.
We Do NOT Use Data For
- Selling to third parties
- Marketing or promotional communications
- Automated decision-making or profiling that affects your rights
- Any purpose beyond what is described in this policy
6. Third-Party Services
Google AdMob
We use Google AdMob (operated by Google LLC / Google Ireland Limited for EU/EEA users) to serve ads. AdMob acts as a data processor on our behalf and as an independent data controller for its own purposes. AdMob may collect advertising identifiers and usage data per their own policies.
PostHog
We use PostHog (PostHog, Inc., United States) for product analytics, session replays and error tracking, as described in Section 2. PostHog's practices are governed by the PostHog privacy policy.
Our referral service (observin.dev)
Referral links are verified by a small worker we run on observin.dev. It receives a random device key, the referral code and the app name so Photons can be credited once per install. It stores no name, email or photo.
Cloudinary (Showcase only)
If you submit a photo to the Showcase, that image and your caption are uploaded to Cloudinary, which hosts the public gallery. Uploads happen only when you press submit. Cloudinary's practices are governed by the Cloudinary privacy policy.
Google Play Store
The app is distributed via the Google Play Store. Google collects data related to app downloads and purchases per their own privacy policy.
No Other Data Sharing
Beyond the services listed above, we do not share, sell, rent, or transfer your data to any third parties.
7. International Data Transfers
We do not directly transfer your personal data outside your country. However, our third-party service providers (Google AdMob, PostHog) may transfer data internationally. Our PostHog project is hosted in the United States, so analytics events are processed there.
For EU/EEA/UK users, Google relies on the EU-U.S. Data Privacy Framework and Standard Contractual Clauses (SCCs) approved by the European Commission to lawfully transfer data to the United States, as described in the Google Privacy Policy.
8. Data Retention
App Data (Local)
Photos, settings and edit history live on your device; uninstalling the app deletes them. A photo you submit to the Showcase stays in the public gallery until you ask us to remove it.
Analytics Data
Analytics and session-replay data are kept in our PostHog project only as long as needed for the purposes described above, then deleted under PostHog's retention settings.
Ad Data
Ad-related data (advertising identifiers, consent records) is retained by Google AdMob per their own data retention policy. Consent records are retained for as long as required by applicable law.
9. Your Rights
Opt Out of Personalized Ads
You can disable personalized advertising at any time:
- Android: Settings → Google → Ads → Delete advertising ID or Opt out of Ads Personalization
Data Deletion
Uninstalling the app removes everything it stored on your device. To delete analytics events linked to your app identifier, or a Showcase upload, contact us (Section 13) and we will remove them. Data held by Google AdMob can be managed with Google's data deletion tools.
Camera & Photo Permissions
You can revoke the photo, camera and location permissions at any time via Android Settings → Apps → Trailium → Permissions. Processing that needs your photos stops without photo access, and Tonight's Sky asks for a location again without location access.
10. Additional Rights for EU/EEA/UK Users
Under the General Data Protection Regulation (GDPR)
If you are located in the EU, EEA, or UK, you have the following rights under the GDPR. You may exercise them by contacting us (see Section 13):
Right of Access (Art. 15)
You can request a copy of the personal data we hold about you and information about how it is processed.
Right to Rectification (Art. 16)
You can request that inaccurate or incomplete personal data we hold about you be corrected.
Right to Erasure / 'Right to be Forgotten' (Art. 17)
You can request that we delete your personal data where there is no compelling reason to continue processing it.
Right to Restriction of Processing (Art. 18)
You can request that we restrict how we process your data in certain circumstances (e.g., while a complaint is investigated).
Right to Data Portability (Art. 20)
You can request that we provide your personal data in a structured, machine-readable format, or transfer it directly to another controller.
Right to Object (Art. 21)
You can object at any time to processing based on our legitimate interests. You also have the right to object to processing for direct marketing purposes.
Right to Withdraw Consent (Art. 7(3))
Where processing is based on your consent (e.g., personalized ads), you can withdraw consent at any time without affecting the lawfulness of prior processing.
Right Not to be Subject to Automated Decision-Making (Art. 22)
We do not use your data for automated decision-making or profiling that produces legal or similarly significant effects.
Right to Lodge a Complaint: If you believe we have violated your data protection rights, you have the right to lodge a complaint with your local data protection supervisory authority. In the EU, you can find your national authority at edpb.europa.eu. In the UK, the supervisory authority is the Information Commissioner's Office (ICO).
11. Children's Privacy
Trailium is not directed at children under the age of 13 (or 16 in some EU member states). We do not knowingly collect personal information from children.
If you believe a child has provided us with personal information, please contact us immediately so we can take steps to delete such information.
12. Changes to This Policy
We may update this Privacy Policy from time to time to reflect changes in our practices or applicable law. When we make material changes, we will update the "Last updated" date at the top of this page and, where required by law, notify you through the app.
We encourage you to review this policy periodically. Continued use of the app after changes constitutes acceptance of the updated policy.
13. Contact & Complaints
If you have questions about this privacy policy, want to exercise your data rights, or wish to raise a concern, please contact us through the link below.
We will respond to all requests within 30 days (or as required by applicable law).
Contact Us