Circa: Health Intelligence
Sleep, stimulants & insights
Only for iPhone
Free · Designed for iPhone. Not verified for macOS.
iPhone
Circa logs supplements, caffeine, and nicotine, pairs them with your Fitbit data, and forecasts tonight's sleep with audited correlations. On-device, no account, ads.
Circa is an iPhone app that logs your supplements, caffeine, and nicotine in two taps and pairs them with your Google Fitbit Air data to turn the two into trend insights, audited correlations, and a live forecast for tonight's sleep. Everything is computed on your iPhone. There is no Circa account and no Circa server. Circa is free and shows advertising, which is loaded over the network.
PRECISE INPUTS
Log anything in two taps: exact dose, exact unit, exact time. Your stack is a shortcut, never a constraint — type any amount, switch units freely (mg, g, µg, IU, pouch, ml, drops). One-tap logging from the Lock Screen widget, or just tell Siri "Log an espresso in Circa."
STIMULANT PHARMACOKINETICS
Live caffeine and nicotine decay curves against your bedtime, with the 50 mg caffeine threshold drawn where it matters. See what this afternoon's espresso still costs you at 23:00.
AUDITED INSIGHTS
Every effect ships with its receipts: n, 95% confidence interval, p-value, correlation — and the actual nights behind it as a scatter plot. Insights that fail their interval for 14 days are retired automatically. Honest null results included.
TONIGHT, FORECAST
A transparent driver model predicts tonight's sleep score and deep-sleep minutes from what you actually did today. Every driver shows its signed contribution. It recomputes on every log — watch the number move.
A 104-SUPPLEMENT LIBRARY
Goal-ranked, evidence-graded, interaction-flagged. Pick your goals and the library re-ranks itself around you.
YOUR DATA STAYS YOURS
Health data is read from the Google Health API and processed entirely on-device. Disconnecting revokes access and erases everything. Export anytime as CSV and JSON.
Explore the full app in demo mode before connecting anything.
Circa is a personal tracking tool, not a medical device. It does not diagnose, treat, or prevent any condition. Requires a Google Fitbit Air and a Google account for live data; manual logging and demo mode work without one.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Circa now shows ads. A banner sits between the content and the tab bar on today, body and signals, and a full screen ad appears after you have actually logged an intake, once the sheet has closed. A sheet you cancel does not count.
There is no banner on log, because its explore segment carries a search field.
Circa has no in-app purchase and no paywall, so there is nothing you can buy to remove the ads. That is worth saying plainly rather than pointing you at an upgrade that does not exist.
Everything else works as before. Your logging, the audited insights and tonight's forecast are still computed on your iPhone.
Where consent for ads is required, Ad privacy settings sits in your profile under About and can be changed at any time.
The developer, Levin David Schwab, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Used to Track You
The following data may be used to track you across apps and websites owned by other companies:
- Identifiers
- Usage Data
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Health & Fitness
- Identifiers
- Usage Data
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Levin David Schwab
- Size
- 7.5 MB
- Category
- Health & Fitness
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
13+
- 13+
- Infrequent
Medical Treatment information
Alcohol, Tobacco, Drug Use or References
Contains
Advertising
Health or Wellness Topics
- Copyright
- © 2026 Levin Schwab