Moonphase Setter vs Ratekeeper
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Moonphase Setter
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Complete the Universe on Your Wrist. A moonphase watch is at its most beautiful when it shows the moon that's actually in the sky. Moonphase Setter tells you exactly how far to move it, and guides you through every turn or press. ■ How it works 1. Take a photo of your watch dial. 2. Line up the moon on the dial with the target moon, by hand or with AI analysis. 3. Follow the instruction: how many times to turn the crown, press the corrector or pusher, or turn the hands. ■ Step-by-step adjustment guide • Supports crown, corrector, pusher and hand-rotation movements • Crown that can turn backward? The shorter direction is suggested • Tap a counter with each turn or press so you never lose count • Re-take a photo afterwards to verify the result ■ Protects your movement Between 9 PM and 3 AM many movements are changing the date or moonphase, and adjusting can strain the gears. The app warns you during this window, in your observation location's time zone. ■ My Watches • Save each watch with its adjustment method and photo, and start your next sync in a tap • Re-sync reminders: the app estimates how far each watch has drifted since its last sync, from its gear train, and lets you know when it's about a day off ■ AI watch identification Not sure how your watch is adjusted? Identify it from your photo, then open its manual to check the moonphase setting. ■ Moon calendar See a whole month of moons with each new moon, quarter and full moon, and jump to any date. ■ Accurate for where you are The moon is calculated for your location and time zone. Use GPS or search for any place, with a southern-hemisphere view when you need it. ■ Premium More daily AI analyses, unlimited watches and no ads. The adjustment guide, danger-time warnings, manual verification and re-sync reminders are always free. Adjustment methods vary by model and movement; please check your watch manufacturer's manual for details. Give your timepiece the gift of perfect synchronization. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://moonphase.moreflow.app/privacy.html
Ratekeeper
Measure the daily accuracy of your mechanical watch without specialized equipment. Simply tap when your watch's second hand aligns with true time, and the app calculates its rate. Track historical data, compare against specifications, and analyze performance by resting position.
- Measures watch rate in seconds per day
- Historical data tracking and charting
- Comparison against specified accuracy bands
- Analysis of rate by resting position
- Standalone true-time reference clock
- Export readings to CSV
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Every mechanical watch has a rate: a few seconds gained or lost each day, as personal to the movement as a fingerprint. Ratekeeper tells you what yours is, exactly, without a timing machine or a trip to the watchmaker. The method is a five-second pleasure. Set your watch to true time. A day or two later, tap the screen the instant the second hand crosses twelve. Ratekeeper compares that tap to atomic network time (accurate to hundredths of a second) and, from two readings, works out the watch's rate in seconds per day. Gaining or losing, and by exactly how much. That's the whole thing. No microphone, no cradle, no gear. Just your watch, your phone, and a tap. WHAT YOU SEE • The rate, plainly. "+5.4 spd". In words, "gains 5.4 seconds a day," so the sign never has to be decoded. • A history that reads like a story. Every reading is grouped into runs (a run begins each time you set the watch) and charted so you can watch a rate settle in as a fresh service beds down, or drift as it comes due for one. • Against a band, if you want one. Hold a watch to −4/+6 seconds a day, or the tighter 0/+5, and see at a glance whether it's keeping to spec. • By resting position. Dial up, crown down, on the wrist: a mechanical watch runs differently in each. Ratekeeper breaks the rate down position by position and even suggests how to rest it tonight to bring it closer to true. • A true-time reference clock. A standalone screen showing network time to the tenth of a second, so you can set any watch against it. BUILT FOR PEOPLE WHO CARE ABOUT WATCHES • Manual, automatic, quartz, or something else: each is measured on its own terms. • Gentle reminders on your rhythm, so readings land a few days apart the way the math wants. • Export every reading to CSV whenever you like. The data is yours to keep. PRIVATE BY DEFAULT No account. No sign-up. No ads. Your watches and readings live on your device and sync across your own devices through your own private iCloud. We can't see them, and nobody is building a profile out of your collection. Find out how your watches really run. Every one of them has a rate. This is how you learn it. Have questions? We're here to help. Email us at hello@slowsundaysoftware.com Terms of Use: https://slowsundaysoftware.com/terms Privacy Policy: https://slowsundaysoftware.com/privacy
Screenshots
Verdict
The clearest difference is ads: Ratekeeper at none against Moonphase Setter's shown. Ratekeeper also leads on update cadence (every 3 days vs every 3 weeks). Moonphase Setter's advantage is iOS requirement (16.6 vs 26.5). On price, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Moonphase Setter sells 2 in-app purchases, starting at $2.99 per month and Ratekeeper sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
Moonphase Setter ships an update every 3 weeks, Ratekeeper every 3 days. The most recent releases landed on November 5, 2026 and October 31, 2026 respectively.
| Parameter | Moonphase Setter | Ratekeeper |
|---|---|---|
| Price | Free | Free |
| Rating | — | 5.0 (2 ratings) — better |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | — | 2 — better |
| Update frequency | Every 3 weeks | Every 3 days — better |
| Ads | Yes | No — better |
| In-app purchases | Yes | Yes |
| Monetization | — | Free |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 16.6 — better | 26.5 |
| Further details — not scored | ||
| Size | 68 MB | 7 MB |
| Age rating | 4+ | 4+ |
| Developer | WOORAM YANG | Slow Sunday Software LLC |
In-app purchases
Moonphase Setter
- Premium Monthly Membership$2.991 Month
- Premium Yearly Membership$9.991 Year
Ratekeeper
- Unlock the entire app$4.99
Questions
Is Moonphase Setter free?
Is Ratekeeper free?
Do Moonphase Setter or Ratekeeper have ads?
Which is updated more often, Moonphase Setter or Ratekeeper?
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