Privacy Policy
Last updated: 25 August 2026
SlumberBrew keeps your data on your device. There is no SlumberBrew account, no SlumberBrew server, and no copy of your coffee log anywhere except the iPhone you logged it on, or the browser you logged it in.
That is the whole policy. The rest of this page explains what that means in practice, and what the exceptions are.
This policy covers both the iPhone app and the website at slumberbrew.com, including the free web tracker.
The website
The web tracker at slumberbrew.com/try stores what you log in your browser's local storage. It is not sent anywhere. There is no account, and we have no way to see it.
Clearing your browser data removes it, and so does the "Delete everything" button on the tracker's Settings tab. Local storage is per-browser and per-device, so what you log on your laptop will not appear on your phone.
The site has no analytics, no cookies, no tracking pixels and no advertising. It sets no cookies at all. Pages are static files and nothing you do on them is logged by us.
Whoever hosts the site will keep standard server logs, which typically include IP addresses and are used to serve the site and defend it from abuse. We do not use those logs to build any profile of you.
Who we are
SlumberBrew is made by Cael Jones, a sole developer based in the United Kingdom. For anything in this policy, contact cmjonesapps90@gmail.com.
What the app stores, and where
Everything the app knows about you lives in a shared container on your device, in three files:
| What | Where it lives | What's in it |
|---|---|---|
| Your drink log | log.json | Every drink you've logged: name, caffeine in mg, and the time you had it |
| Your sleep ratings | ratings.json | The 1 to 5 rating you give a night, and how long it felt like it took to drop off |
| Your settings | settings.json | Bedtime, wake time, half-life, targets, quick-add drinks, custom drinks, theme |
The container is shared between the app and its home screen widget, which is how tapping a drink on the widget updates the number in the app. It is not shared with anything else, and it is not backed up to any server we run.
If you have iCloud Backup switched on, iOS may include this container in your device backup. That backup is between you and Apple. We can't see it, and we can't restore from it.
Apple Health
If you connect Apple Health, two things happen, both of which you control.
SlumberBrew reads your sleep. It looks at up to the last 90 days of sleep analysis so it can show you how caffeine at bedtime lines up with how you actually slept. That data is read on your device, used on your device, and never sent anywhere.
SlumberBrew can write the drinks you log back to Health as dietary caffeine, so the rest of your health record stays complete. It writes nothing else. It never reads any health data other than sleep.
You can turn either direction off at any time in the iOS Settings app under Privacy & Security › Health › SlumberBrew. Health data is never used for advertising, never sold, and never shared with anyone.
If you want to remove caffeine SlumberBrew has already written to Health, you can do it in the Health app under Browse › Nutrition › Caffeine.
Notifications
The caffeine curfew alert and the morning sleep check are scheduled on your device by iOS. They are not push notifications. Nothing is sent to a server to make them happen, and no one else knows when they fire.
What we collect about you
Nothing. As of version 1.0, SlumberBrew makes no network requests at all. It has no analytics, no crash reporting, no advertising identifiers, and no tracking of any kind. It does not ask for the App Tracking Transparency permission because there is nothing to track.
The app contains links to the research it cites. Tapping one opens your browser and takes you to a publisher's website, at which point their privacy policy applies, not ours.
Analytics (if enabled in a future version)
This section applies from the version in which product analytics ship. It does not apply to version 1.0.
We use PostHog, hosted in the European Union, to understand how the app is used: which features people reach, where they get stuck, and whether the widget actually gets used. Events record counts and actions, never content.
We do not send PostHog your caffeine amounts, your drink times, your sleep ratings, your bedtime, or anything read from Apple Health. Health data never leaves your device under any circumstances.
PostHog processes this on our behalf as a data processor. Their privacy information is at posthog.com/privacy.
Purchases (if enabled in a future version)
This section applies from the version in which in-app purchases ship. It does not apply to version 1.0.
Purchases are handled by Apple. We use RevenueCat to check whether a subscription is active. RevenueCat receives a purchase receipt and an anonymous identifier. It does not receive your name, your email, or any data from the app. Apple handles your payment details and never shares them with us. RevenueCat's privacy policy is at revenuecat.com/privacy.
Your rights
Because your data never leaves your device, most data rights are things you can exercise yourself, immediately, without asking us:
- Access and portability. Settings › Data › Export your data writes everything the app holds to a JSON file you can save or send wherever you like.
- Erasure. Settings › Data › Delete everything removes your log, your ratings and your settings, and returns the app to a fresh install. Deleting the app does the same thing. On the website, the Settings tab of the tracker has the same button, and clearing your browser data also works.
- Rectification. You can edit or delete any individual entry in either version.
If you're in the UK or the EU and you believe we've mishandled your data, you can complain to your national supervisory authority. In the UK that's the Information Commissioner's Office at ico.org.uk.
Children
SlumberBrew isn't aimed at children and we don't knowingly collect anything from anyone. Caffeine guidance for adults doesn't transfer to children, and the app says so where it matters.
Changes to this policy
If this policy changes in a way that affects what happens to your data, the change will be described in the app's release notes rather than quietly published here. The date at the top always reflects the current version.
Contact
cmjonesapps90@gmail.com