Written by the team behind HeySis, one of the apps discussed. This comparison is based on official feature documentation.
HeySis core features will always remain free. Premium is optional and unlocks additional features.
Consider HeySis for an on-device diary, free doctor PDF and AI questions. Stardust offers Oura connectivity, social features and a lunar-themed experience. Both have free tracking and screenshot import; access conditions and data handling matter.
Prices and subscriptions
US App Store · USD · checked September 12, 2026
HeySis
Core features · always free
$0
Optional Premium
$24.99 / year
Monthly Premium: $5.99/month. It unlocks more AI messages, deeper insights and additional features.
Core features will always remain free. Annual Premium works out at about $2.08/month, billed yearly. The $17.99/year offer has separate eligibility.
Stardust
Basic cycle tracking · free
$0
Optional Super
$29.99 / year
Monthly Plan: $6.99. The store also lists trial-linked annual offers at $24.99 and $39.99.
Annual Plan is explicitly labeled. Eligibility and renewal can differ between offers.
The compared trackers offer basic tracking without a subscription. Prices vary by country, account and offer. Annual plans are paid upfront; monthly equivalents are calculations, not monthly billing.
Feature comparison at a glance
Availability and plan conditions matter as much as the feature itself.
| Feature | HeySis | Stardust |
|---|---|---|
| Period diary | Always free · basic period, symptom and mood tracking | Free · period and symptom tracking |
| Assistant | AI chat with a free limit; Premium raises the limit | AI is mentioned; chat access is not specified in these sources |
| Doctor report | Free · generated on the phone, excludes AI chats | PDF export is not documented in these sources |
| Bring your history | Calendar screenshot recognition on iPhone; separate Health import | Screenshot upload during onboarding; servers delete images after transfer |
| Sharing with a partner | Circle invites and basic status are free; deeper member insights are Premium | Partner Mode and Friend Sync |
| Privacy choices | On-device diary; AI, sync and Circle are separate online choices | States no data sale; health data separated from contact identity |
| Devices | iPhone · iOS 26+; permission-based Apple Health integration | iOS and Android; Apple Health and Oura connections |
| Pregnancy | Weekly information and logs; selected illustrations and weight analytics are Premium | Divine Creator Mode · pregnancy experience |
| Paid extras | More AI messages, insights, article library and selected Circle features | Super · phase-based content, Cyclepedia, Signal Sync and symbolic readings |
Sources for prices and features: HeySis · App Store US · Stardust · App Store US · Stardust · App features · Stardust · Free features, import and integrations · Stardust · Your data · HeySis
Where each tracker has an advantage
Try HeySis for a free doctor PDF and an on-device diary. Stardust is worth considering for its Oura connection and social, lunar-themed experience. Both offer screenshot import; compare how the images are processed.
Everyday period tracking
HeySis lets you log periods, symptoms and mood, revisit the calendar and prepare with reminders. The core diary works offline and will always remain free. You can establish a recording habit before deciding whether deeper insights are useful.
Stardust centers its experience on cycle phases, daily content and lunar symbolism. Choose a style that makes you want to return. An engaging explanation of a phase does not establish prediction accuracy.
Both apps import screenshots
HeySis recognizes logged period days on your iPhone. Select up to four calendar screenshots with visible month and year labels, then review the dates. This does not transfer every note or symptom.
Stardust offers screenshot upload during onboarding and says it deletes the images from its servers after transfer. Import is a shared capability; image processing differs. Keep your original history and compare recorded dates rather than predictions when switching.
Sharing with partners and friends
HeySis Circle invitations and basic status sharing are free. Detailed member insights and selected interactions require Premium; an invited companion does not need a separate paid subscription.
Stardust offers Partner Mode and Friend Sync. Try inviting someone, viewing the shared information and removing access together. The useful test is whether the app shares exactly what you intended.
Doctor reports, AI and integrations
HeySis assembles a free PDF on your phone from recent cycles and diary entries, excluding AI conversations. Online assistant answers require consent and use relevant context; Premium increases the free message allowance.
Stardust documents Apple Health and Oura connections. We did not find a downloadable doctor PDF described in the reviewed material. That does not establish its absence: verify this workflow before paying if it is essential to you.
Free tracking and optional subscriptions
You can start recording your cycle before choosing paid extras. HeySis core features will always remain free. Stardust supplements free tracking with more detailed Super content. The price cards above separate US store products and offer conditions.
Judge a subscription by a task: does it help you discuss entries, revisit recurring observations or find useful reading? A monthly equivalent for an annual plan still means paying for the year upfront.
Data handling and choosing your tracker
HeySis stores the diary on the device by default; online AI, sync and Circle involve separate data flows. Stardust states that it does not sell data and separates contact information from health records. These are publisher statements, not independent security audits.
Choose around your routine: logging, importing, sharing or preparing for an appointment. Predictions are estimates; HeySis is not intended for contraception or diagnosis.
Sources and review
Checked September 12, 2026. Prices, regions, plans and feature rollouts can change. We do not label a feature absent just because a source does not mention it.