LSTclock vs GPSTime
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
LSTclock
This utility app displays local sidereal time for registered locations on iOS, iPadOS, and watchOS. It can also calculate sidereal time and Julian Date for any date and time, and sync locations between devices.
- Local sidereal time display
- Julian Date calculation
- Supports multiple registered locations
- Location sync between iPhone and Apple Watch
- Date and time specific calculations
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LSTclock is an iOS/iPadOS/watchOS app that displays the local sidereal time (LST) at registered location(s). On iOS/iPadOS, it can also calculate LST and Julian Date for any date and time. The list of locations can be synced between iPhone and paired Apple Watch(es).
GPSTime
This tool converts between GPS Time and UTC, supporting various formats like GPS Week, Gregorian calendar, and Modified Julian Date. It accurately handles leap seconds and saves conversion history for GNSS professionals, researchers, and students.
- GPS Time to UTC conversion
- Support for leap seconds
- Multiple time format support
- Conversion history saving
- Configurable default scenarios
- Clean interface
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GPSTime is a time conversion tool designed for researchers, students, and GPS/GNSS professionals. Time conversion is a frequent challenge in GNSS work—whether parsing broadcast ephemerides, handling IGS product names, or aligning observation data. GPSTime streamlines this process by providing accurate conversions between GPS Time and UTC, with full support for leap seconds. The app supports a wide range of commonly used formats, including: • GPS Week + Time of Week (TOW) • GPS Week + Day of Week (DOW) • Gregorian calendar (YYYY-MM-DD HH:MM:SS) • Year + Day of Year (DOY) • Modified Julian Date (MJD) Using historical leap-second data, GPSTime ensures correct handling of the GPS–UTC offset for both past and present times. GPSTime is also capable of saving your conversion history (up to 200 logs in the History tab) and lets you configure default conversion scenarios to match your most frequently used time system and format. With a clean interface and multiple input/output options, GPSTime is an essential companion for GNSS research, education, and precise timekeeping tasks.
Screenshots
Verdict
The clearest difference is rating: GPSTime at 5.0 against LSTclock's 3.8. GPSTime also leads on update cadence (every 2 weeks vs every 2 months). LSTclock's advantage is ratings volume (10 vs 1). On price, ads, in-app purchases and monetization model 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. Neither carries in-app purchases, so what you see is what you pay.
GPSTime holds the better App Store score, 5.0 against 3.8. That said, the two scores are not equally well evidenced: LSTclock has 10 ratings behind it against 1, so its average is the more settled of the two.
LSTclock ships an update every 2 months, GPSTime every 2 weeks. The most recent releases landed on September 9, 2026 and June 2, 2026 respectively.
| Parameter | LSTclock | GPSTime |
|---|---|---|
| Price | Free | Free |
| Rating | 3.8 (10 ratings) | 5.0 (1 ratings) — better |
| Positive reviews | 54.5% of reviews | — |
| Number of ratings | 10 — better | 1 |
| Update frequency | Every 2 months | Every 2 weeks — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad, Apple Watch | iPhone, iPad, Mac |
| Requires iOS | 17.0 — better | 18.5 |
| Further details — not scored | ||
| Size | 15 MB | 25 MB |
| Age rating | 4+ | 4+ |
| Developer | Tsuyoshi Sawada | Gimin Kim |
Customer experience
LSTclock
GPSTime
In-app purchases
LSTclock
No in-app purchases
GPSTime
No in-app purchases
