Delta ("we," "us," or "our") is a personal health coaching application. This Privacy Policy explains what data we collect, how we use it, how we store and protect it, and what rights you have over it. We have written this policy to be direct and specific — not vague.
By using Delta, you agree to the practices described in this policy. If you do not agree, please discontinue use of the app and contact us at hello@usedelta.app to request deletion of your data.
1. What data we collect
Delta collects the following categories of health and biometric data when you connect the corresponding integrations:
From Apple Health (on-device, via HealthKit):
- Workout sessions: type, duration, active energy burned, heart rate data
- Step count and daily activity
- Body weight (most recent record)
- Other metrics you explicitly authorize in the HealthKit permission dialog
From Oura Ring (coming soon, via Oura OAuth API):
- Sleep data: total sleep duration, sleep stages (deep, REM, light, awake), sleep efficiency, sleep timing, and Oura's sleep score
- Heart rate variability (HRV): nightly average and daily mean
- Resting heart rate (RHR): nightly average and daily mean
- Readiness score and its contributing factors
- Activity score, daily movement, and calorie estimates
- Body temperature deviation (when available)
From Peloton (coming soon):
- Workout history: ride and class type, duration, output, and heart rate data
Nutrition data (entered by you):
- Meal descriptions and food entries you log via natural language in the app
- Parsed macro and calorie estimates derived from your entries
Account data:
- Email address and password (used for authentication via Supabase Auth)
- Profile settings: age, sex, height, weight, goal profile, and units preference
- Push notification token (if you enable notifications)
2. How we use your data
We use your data solely to operate Delta and provide you with coaching. Specifically:
- To compute your daily recovery, training load, acute:chronic workload ratio, and session strain scores
- To generate your personalized morning coaching brief
- To track nutrition totals and trends against your goals
- To display your historical data and score trends in the app
- To deliver push notifications when your brief is ready
A portion of brief generation is handled by Claude AI (Anthropic). When generating brief text, we send Anthropic an anonymized summary of your daily metrics — aggregated scores and contextual figures such as HRV, readiness, and training load. We do not send raw timestamped health records, your name, your email, or any other personally identifying information to Anthropic. Anthropic's use of this data is governed by their privacy policy.
3. Where your data is stored
Your data is stored in a Supabase database hosted on Amazon Web Services (AWS) infrastructure. All data is encrypted at rest using AES-256 and encrypted in transit using TLS 1.2 or higher. Access to the database is restricted to authenticated application services; no human staff has routine access to your health records.
Apple Health data is processed on your device by the Delta iOS app. Summaries and scores derived from that data are uploaded to our servers. Raw HealthKit records are not transmitted in full — only the derived values Delta needs for scoring.
4. Third-party processors
The following third-party services process data on our behalf:
- Supabase — Database, authentication, and server infrastructure. Supabase stores your account data and health metric summaries on AWS. Supabase Privacy Policy
- Anthropic (Claude AI) — Receives anonymized daily metric summaries (not raw health data) for the purpose of generating coaching brief text. Anthropic Privacy Policy
- Oura Health Oy (coming soon) — Will provide your Oura Ring data via their official OAuth API. We will access only the data you explicitly authorize. Oura Privacy Policy
- Apple — HealthKit data is accessed on-device via Apple's HealthKit framework, under the permissions you grant in iOS Settings.
No other third parties receive your data.
5. Data retention
Your data is retained for as long as your account is active. If you delete your account, all associated health data, scores, briefs, and profile information are permanently deleted within 30 days. Anonymized aggregate statistics that cannot be traced back to you may be retained for internal analysis.
You may also request deletion of specific data categories (for example, all Oura data) without deleting your entire account by contacting us at hello@usedelta.app.
6. How to disconnect integrations
You can disconnect any integration at any time from the app's Settings > Integrations screen. Disconnecting an integration immediately stops Delta from fetching new data from that source. It does not automatically delete previously synced data; to delete historical data from a disconnected integration, contact us at hello@usedelta.app.
When Oura integration is available, you will be able to revoke OAuth authorization independently of Delta from your Oura account settings at cloud.ouraring.com under Connected Apps.
To revoke Apple Health permissions, go to the iOS Settings app, then Privacy & Security > Health > Delta, and toggle off any data categories.
7. Your rights
You have the right to:
- Access — request a copy of all data Delta holds about you
- Correction — request correction of inaccurate profile data
- Deletion — request deletion of your account and all associated data
- Export — request an export of your data in a machine-readable format (JSON or CSV)
- Objection — object to any processing you did not consent to
To exercise any of these rights, contact us at hello@usedelta.app. We will respond within 30 days.
8. Children
Delta is not intended for use by individuals under the age of 16. We do not knowingly collect data from anyone under 16. If we learn that we have inadvertently collected data from a person under 16, we will delete it promptly. If you believe this has occurred, please contact us at hello@usedelta.app.
9. Changes to this policy
If we make material changes to this Privacy Policy, we will notify you by email at the address associated with your account at least 14 days before the changes take effect. Continued use of Delta after that date constitutes acceptance of the updated policy. Non-material changes (such as clarifications or formatting) may be made without notice. The effective date at the top of this page will always reflect the most recent revision.
10. Contact
For any privacy-related questions, requests, or concerns, contact us at:
hello@usedelta.app
Delta — usedelta.app