Privacy Policy

Last updated: 16 September 2026

LumenLog is designed to be private by default. This policy explains how your check-ins, notes, care habits, settings, and reflections are stored, synced, and used for generated insight features. LumenLog is the data controller for processing performed to provide the app and website. Privacy questions can be sent to hello@lumenlog.app.

Where your data is stored

Your complete LumenLog journal is stored on your device. If iCloud is enabled for LumenLog, it may sync through your Apple iCloud account so it remains available across your Apple devices. Apple processes that synced data under your relationship with Apple. LumenLog does not operate a central journal database.

Device protection

LumenLog can use passcode and Face ID lock to help protect the journal on your device. You are still responsible for keeping your device, passcode, and Apple ID secure.

AI-powered insights

Generated insights require selected context to leave your device. Depending on the insight, this can include calendar days, reflection windows, mood selections, completed habit titles, current active habit titles, your chosen insight tone, and a limited number of recent check-ins. LumenLog removes names, internal check-in and habit identifiers, habit prompts, presentation symbols, exact check-in times, the transport-only morning or evening slot, and device locale from the context sent to the AI model.

Note text is excluded by default. It is included only after you explicitly enable richer insight detail in Settings. Notes may contain identifying or sensitive information, so do not enable this option or enter information you do not want processed for the generated response.

How insight requests are processed

Insight requests travel over HTTPS through LumenLog's stateless API hosted by Vercel in its London region and are then sent to Google Gemini. LumenLog's API does not add request bodies, prompts, notes, habits, or generated insight text to application logs or a database. Operational logs contain information such as request identifiers, insight type, timings, model status, token counts, errors, and rate-limit status.

Google processes the minimised prompt and generated response. Under Google's paid Gemini API terms, prompts and responses are not used to improve Google's products. Under the standard abuse-monitoring terms, Google may retain prompts and responses for up to 55 days to detect policy violations and meet legal or regulatory requirements. Google states that processing may occur in countries where Google or its agents operate. Generated insight text may be stored by LumenLog only on your device and in your iCloud account.

Security and rate limiting

The app sends a random installation identifier to prevent excessive use of the insight service. The identifier is not your name, email address, Apple ID, or journal content. It is hashed before being used for rate-limit counters. Where Upstash Redis is enabled, only the hash and temporary counters are stored there. Network providers may also process IP addresses and ordinary request metadata to deliver and protect the service.

Exporting and deleting data

You can export your data or delete it from inside LumenLog. Deleting local data removes it from the app on that device. If iCloud sync is enabled, follow the in-app prompts and iCloud behavior carefully so synced copies are handled as expected.

Purchases

LumenLog subscriptions are processed through Apple and the App Store. LumenLog does not receive your payment card details.

Website analytics

The LumenLog website uses Vercel Web Analytics to understand aggregate page usage and technical performance. Website analytics are separate from your LumenLog journal and do not receive check-ins, notes, moods, or habits.

Your choices and rights

You can keep note text out of generated insights, disable richer insight detail at any time, export your journal, and delete your data in the app. Depending on where you live, you may also have rights to request access, correction, restriction, objection, or deletion of personal data processed by LumenLog. Contact hello@lumenlog.app to make a request.

Contact

For privacy questions, email hello@lumenlog.app.