Privacy policy

Effective 15 October 2026

Circa is an iPhone and Apple Watch app for fasting, food, drinks and water, drawn on a 24-hour dial with your sleep and workouts from Apple Health. It is made by Alex Priest, an individual developer. This page says what Circa stores, what leaves your phone, and where it goes.

On your iPhone and Apple Watch

Circa keeps its records as files and settings on your device: your fasts and the one running now, drinks, meal types, fasting schedules and plans, nights you planned to skip drinking, your own foods and recent foods, and your preferences. Newer versions also keep daily goals and recipes. The Home Screen and Lock Screen widgets read a copy of today's dial from storage shared between Circa and its widgets on the same phone. This on-device data can be included in your own iPhone backups.

Your iPhone and Apple Watch keep each other up to date through Apple's WatchConnectivity, which passes data, including some settings, between your paired devices. Circa does not route it through its server.

Camera photos of meals are held only while you review them and are not saved by Circa. When you say what you ate, Apple's speech framework turns it into text on your iPhone; the audio is not sent anywhere.

Reminders, such as reaching a fasting goal or a nudge to drink water, are scheduled on your phone. Circa does not use push notifications.

Circa writes short diagnostic messages to your device's system log. These can include the contents of a barcode it couldn't read.

iCloud

If you are signed in to iCloud, Circa copies these records to its own folder in your iCloud Drive so your devices share them: fasts, the running fast, drinks, meal types, fasting schedules and plans, skipped-drink nights and, in newer versions, daily goals. That folder belongs to your Apple Account and is covered by Apple's iCloud terms. I can't see it. Your food library is not synced through iCloud Drive. Circa's settings show whether iCloud is available.

Apple Health

Circa asks for Health access in one request, and Apple's sheet lets you allow or refuse each type separately. You can change any of it in the Health app or in Settings › Health › Data Access & Devices › Circa.

What Circa reads

• Sleep.
• Workouts, with their active energy and walking, running, cycling and swimming distance.
• Dietary energy, protein, carbohydrates and fat, water and caffeine, including the details attached to food entries.
• Body weight.
• The alcoholic-drink entries Circa itself saved.
• In newer versions, only if you turn them on: steps, time in daylight and mindful minutes.
• In newer versions, only if you turn on cycle tracking: menstrual flow, spotting, and the symptoms Circa offers (cramps, bloating, headache, fatigue, breast pain, acne, lower back pain, nausea, hot flashes, mood changes, sleep changes and appetite changes).

What Circa writes

Circa saves to Health only what you log in it:

• Foods you log, as food entries with energy, protein, carbohydrates, fat, fibre, sugar and sodium where known.
• Water, and the caffeine in coffee and tea, from the iPhone or the watch.
• Alcoholic drinks, with their estimated energy and carbohydrates.
• Workouts you add or edit, with active energy.
• In newer versions, mindful sessions you log, and cycle days you log if cycle tracking is on.

Cycle tracking is off until you turn it on. Circa keeps cycle information out of its widgets, exports, sharing and watch messages, and does not copy it to iCloud Drive. Health stores it the way it stores everything else.

Health data that Circa reads is used to draw the dial and its history on your device. Circa doesn't upload Health samples to its server or to Anthropic. A picture of a day that you choose to share can show Health information.

Food estimates from Claude

Circa can estimate a meal from a photo or from words you type or say, using Claude, an AI model made by Anthropic. This is off until you allow it. Circa asks the first time you take a meal photo, or the first time a description has foods Circa can't match on the phone. You can turn it off again in Circa's settings, under Estimates from Claude (Photo estimates in earlier versions).

What is sent

• For a photo: the photo, shrunk to at most 1024 pixels on its longer side and saved again as a plain JPEG with no location, time or camera details.
• For words: the food phrases that need an estimate and any other words you gave for the same meal.
• With either: your language and region setting, such as en_US, so portions are worded the way you'd say them.
• App Attest information that authenticates your installation of Circa, and the usual connection details any internet request carries, such as your IP address.

A photo or description can identify you by what it shows or says. The request goes to Circa's server, a small program on Cloudflare, which passes it to Anthropic's API and returns the estimate. You check every food before anything is saved to Health.

What Circa's server keeps

The server does not save photos, descriptions or food names. It stores:

• An App Attest key for your installation. Circa uses Apple's App Attest to prove a request came from a genuine copy of the app. The key links one installation's requests, usage and spending.
• Daily counts of estimates and searches per installation, to enforce limits. You get up to 30 estimate attempts a day, and failed attempts can count.
• Spending records per request and running spending totals, to keep the monthly cost under a fixed cap.
• Short-lived sign-up challenges and records of requests still in progress.
• One log line per request, holding only a random request ID, the route, the result code, and the token count and cost.

Old daily counts, used challenges and settled spending records are cleared out when later requests arrive, not on a fixed schedule. Installation keys, spending totals and unsettled spending records have no automatic expiry.

The server's code does not record your IP address, and Cloudflare's invocation logs, which record request addresses and details, are turned off for it. Cloudflare still carries the connection, as any web host does.

Anthropic

Anthropic receives the request under its Commercial Terms of Service, which say Anthropic "may not train models on Customer Content from Services." Anthropic says it deletes API inputs and outputs within 30 days, except where it needs to keep them longer to enforce its usage policy or to comply with the law.

Food search and barcodes

Common foods are searched on your phone, from a copy of USDA FoodData Central that ships inside the app.

Packaged foods are searched online. A search starts once you type three characters, not counting spaces. Foods you type or say that the bundled list can't match are also searched automatically. Foods from a photo estimate are not. Circa sends the search words to two places:

• Open Food Facts, directly from your phone. Open Food Facts sees your IP address, the search words and Circa's version number.
• Circa's server, with the same App Attest authentication as estimates. The server forwards the words to USDA FoodData Central's branded-food search, so USDA sees the server, not your phone. The server does not keep or log the words.

When you scan a barcode, Circa first checks foods you have logged before. If it isn't there, the barcode number goes directly from your phone to Open Food Facts. A barcode scan sends no photo.

Food search and barcode lookups do not use Claude and do not need the Claude permission.

Other connections

• App Attest: your phone talks to Apple to set up and confirm the installation key.
• Speech: your phone may download Apple's speech model for your language the first time you use voice.
• iCloud: Apple syncs Circa's iCloud Drive folder, as above.
• Links: web links open in your browser, where that site's policy applies, and optional Shortcuts can open other apps.
• This website loads its fonts from Google Fonts.

What Circa does not do

• No account, sign-in, name or email inside the app.
• No analytics, crash-reporting, advertising or tracking SDKs. Circa contains no third-party code libraries.
• No location access.
• No selling, renting or sharing of your data for advertising. Health data is never used for advertising or marketing, and never given to data brokers.

The TestFlight beta

The beta runs through Apple's TestFlight. Apple, not Circa, collects some information there and shares it with developers: your device, platform and app version, session and crash counts, crash reports, and any feedback and screenshots you choose to send. If you were invited by email, your name and email address are shared with the developer; testers who join by public link appear as anonymous. Apple's own privacy policy covers this. If you email to ask for an invite, I have your email address and use it only for the beta.

Exports and sharing

Circa's settings can export your fasts as a CSV or JSON file. Circa can also make a picture of a day for you to share. Both only happen when you tap them, and the file goes wherever you send it from the share sheet.

Deleting your data

• Deleting Circa from your iPhone and watch deletes the data it keeps on those devices. It does not remove your iPhone backups or copies you exported or shared.
• To remove Circa's iCloud Drive copy, delete Circa's data in your iPhone's iCloud storage settings.
• Data Circa saved to Health stays in Health after you delete the app. You can review and delete it in the Health app, where it is listed under Circa as a source.
• For anything about Circa's server, email privacy@circa.day and I'll help with what the system allows.

Children

Circa is not meant for children under 13, and I do not knowingly collect information from them.

Changes

If Circa starts handling data differently, I will update this page and the date at the top.

Contact

Questions or requests about privacy: privacy@circa.day. Circa is made by Alex Priest, Austin, Texas.