Daylumen is built so your data never has to leave your iPhone. This policy explains exactly what that means.
The short version
- Everything is computed on your device. Daylumen needs no account, and your health data and photos never leave your device.
- Your health data and photos are never uploaded, sold, or shared.
- There are no ads and no cross-app tracking or ad profiling. Daylumen uses anonymous usage analytics (PostHog) to understand how features are used; it's on by default and can be turned off anytime in Settings.
- You can revoke any permission at any time, and deleting the app removes everything.
What Daylumen accesses on your device
Apple Health (HealthKit)
With your permission, Daylumen reads health data such as activity, sleep, heart-rate measures, and related metrics to understand your patterns. It only reads — it never writes to or changes anything in Apple Health.
Photos
With your permission, Daylumen reads recent photos on your device to understand the context of your days (for example, time spent outdoors, travel, or late nights). It extracts only general, de-identified context. Your original photos, faces, and location data are never copied, uploaded, or transmitted.
Location (optional, for weather)
If you allow it, Daylumen uses your approximate location (about 0.1° precision, city level) to request the weather where you are from Apple Weather (WeatherKit). The coordinates are sent to Apple for that request; they are not uploaded to Daylumen's servers. Separately, our analytics provider (see below) estimates an approximate region from your network IP address.
Notifications
If you turn on the optional morning check-in, Daylumen schedules local notifications on your device. Their content is generated on-device and is not sent through any server.
Optional: anonymous usage analytics
Starting with this version, Daylumen uses PostHog (PostHog, Inc.) for anonymous usage statistics. Data is relayed through our domain e.daylumen.com and stored on PostHog's servers in the United States. Together with the optional “Share & Get Membership” campaign below, this is what sends data from your device to us or our providers.
- The following kinds of data are sent: a randomly generated device identifier (not linked to your Apple account, name, or email), and the names of product interaction events (for example, "logged a day," "viewed an insight," the result of a purchase or restore — product ID only, never payment details — whether a flow succeeded and the category of any failure, how long a step took in coarse time ranges (to see which step is slow; no content), permission results).
- Device and environment info (app version, OS version, device model, system language, time zone, screen size, network type) and an approximate region: PostHog estimates your country and city from your IP address, and the IP address itself is not stored.
- We don't record your screen. Only when rapid repeated taps are detected do we log, once, the approximate on-screen position of that tap, to find buttons that don't respond; we never record what was tapped.
- These events never include your health data, photos, journal entries, or any other content you type or that Daylumen reads from your device.
- If Daylumen crashes, PostHog also collects a crash diagnostic report the next time you open the app (the crash type and stack trace, your device model, iOS version, and Daylumen's app version, plus the same random device identifier); it never includes your health data, photos, or journal entries either.
- It's on by default. You can turn it off anytime in Settings → Share & feedback → Anonymous usage analytics; once off, no more events — including crash diagnostics — are sent.
- This data is used only to improve Daylumen itself — it is never used for ad targeting, sold, or combined with data from other apps.
“Share & Get Membership” campaign (optional)
Only if you choose to take part in the in-app “Share & Get Membership” campaign and submit an application does Daylumen send the following to our server (ugc.gatheon.com): the Xiaohongshu (RED) post link you share, an optional email address (you can leave it blank), the install identifier, the app version, system language and App Store region. This is used only to verify your application, grant the membership reward and tell you the result. If you enter an email, the result and any redemption-reminder emails are sent by Customer.io (Customer.io, Inc., United States), which receives your email address and application status for that purpose. The processing status of your application (without the link or email) is also recorded in the anonymous analytics above. Entering or sharing an invite code sends the install identifier, the code, your first-install date and App Store region to verify the referral. None of this happens unless you take part; to delete your application and email, write to [email protected].
How your data is processed
All analysis — reading your health metrics, interpreting photo context, finding patterns, and writing your daily read — happens entirely on your iPhone. Derived results are cached locally on your device so the app opens quickly. None of this is sent off the device.
What we do not do
- We do not upload your health data or photos to any server.
- We do not sell, rent, or share your data with anyone.
- We do not use your data for advertising, and we do not show ads.
- We do not do cross-app tracking or device fingerprinting; the only third-party analytics we use (PostHog, see "Optional: anonymous usage analytics" above) reports only event names, device and environment info, an approximate region and a random install identifier, and can be turned off anytime.
- We do not require an account, email, or sign-in to use the app (the optional “Share & Get Membership” campaign above is the only place an email can be entered, and it is optional).
Health data, specifically
Consistent with Apple’s requirements, information gathered through HealthKit is never used for advertising or marketing, and is never sold or shared with data brokers or third parties. It is used solely to provide the wellness insights you see in the app, on your device.
Medical disclaimer
Daylumen provides general wellness and lifestyle insights. It is not a medical device and does not provide medical advice, diagnosis, or treatment. When a signal is uncertain, the app says so. For any health concern, please consult a qualified professional.
Your control
- You can grant or revoke Health, Photos, and Notifications permissions any time in iOS Settings.
- You can turn off anonymous usage analytics anytime in Settings → Share & feedback → Anonymous usage analytics.
- Daylumen stores its results only in its own on-device cache. Deleting the app permanently removes all of it.
Children
Daylumen is not directed to children under 13, and we do not knowingly collect data from them.
Changes to this policy
If this policy changes, we will update this page and the date above. Because your health data and photos stay only on your device, changes only ever affect what the app does on your device going forward.
Contact
Questions about privacy? Email [email protected].