Zulu Time vs PhaseChecker
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Zulu Time
This app displays local and UTC (Zulu) time, along with multiple time zones, on your iPhone, Apple Watch, and iPad. It offers widgets for quick access and features for calculating future or past times with offsets, simplifying timezone conversions for various professions.
- Display local and Zulu (UTC) time
- Multiple time zone display
- Home and Lock Screen widgets
- Apple Watch complications
- Future/past time offset calculations
- Time zone conversion
Read full descriptionHide full description
An iPhone, Apple Watch and iPad app to see Local and Zulu time (GMT) or multiple time zones in a single glance. Includes Widgets for both the iPhone and Apple Watch. Useful for pilots in getting weather briefings and filing flight plans, or Ham radio operators to do timezone conversions. No more worrying about getting the timezone offset correct or Daylight Savings Time conversions. Easily convert from different time zones, including times in the future or past. On the iPhone: - Home and Lock Screen widgets - The Zulu Time page gives a quick view of both Zulu and Local times - The Offset Time page allows you to see Zulu and local time either in the future or past by entering an offset via the Offset button. Tapping either Zulu or Local times will allow you to enter a time in the future or past, synchronizing both Local and Zulu times with that offset. The offset only applies to this view (except on the iPad the offset applies to everything on the page) - The Multiple Zones page allows you to add as many time zones as you wish in a scrolling view. Clicking on any Time Zone will allow you to change it. on iPad: All information is combined on one screen. You have user customizable time zones on the right hand side. On the left, you have Zulu and Local time and one customizable time zone. The offset to see future or past time can be done via the Offset button or tapping any of either the Zulu, Local or Custom time buttons on the left. On the Watch: Complications available in all watch faces making for glanceable ZuluTime and access to the app, which gives offset able time computation.
PhaseChecker
This utility app tests your sound system to ensure speakers are correctly wired and in-phase. It offers manual and automatic modes, with advanced waveform analysis for precise setup. Proper phasing is crucial for optimal bass response and stereo imaging.
- Speaker phase and polarity testing
- Manual and automatic test modes
- Microphone-based analysis
- Waveform view for advanced users
- In-app help and guidance
- Audio output connection
Read full descriptionHide full description
The PhaseCheck app will run a test signal through your sound system to ensure your speakers are in-phase and wired with the correct polarity. It can be run either manually or automatically. Manual mode allows you to run the test signal and flip the phase so you can listen yourself to ensure your sound system is setup correctly. Automatic mode will run a series of test signals through your sound system and use the microphone on the device to analyse the results. New in version 2.0 is a waveform view mode for advanced use. It allows you to play an asymmetrical waveform (ramp waveform), record the sound from each speaker close up and capture the waveforms to then compare them. Phase is a difficult concept so full help is available in the app to ensure you get the best results. You should check the phase of your sound system whenever the wiring has been changed to ensure everything is the correct polarity. When a sound systems speakers are out of phase the sound quality is affected massively. Bass is reduced significantly and stereo imaging gives the illusion of the sounds pulling outside of the room. To run the check connect your iOS device to your sound system so it can play audio. If possible place the iOS device evenly between the speakers. Phase cancellation will not occur close to the speakers so ensure the device is not too close. Ensure the volume is at a comfortable listening level and if possible ensure there is no background noise to interfere with the scan.
Screenshots
Verdict
The clearest difference is review sentiment: Zulu Time at 79% against PhaseChecker's 16%. Zulu Time also leads on rating (4.8 vs 2.0) and monetization model (free vs paid). PhaseChecker's advantage is iOS requirement (14.1 vs 17.6). On price, ads, 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
Zulu Time costs $0.99 and PhaseChecker $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Zulu Time holds the better App Store score, 4.8 against 2.0. That said, the two scores are not equally well evidenced: Zulu Time has 2.6K ratings behind it against 3, so its average is the more settled of the two. Written reviews point the same way: 79% of Zulu Time's written reviews are positive against 16% of PhaseChecker's.
Zulu Time ships an update every 3 months, PhaseChecker every 43 months. The most recent releases landed on September 24, 2026 and September 17, 2026 respectively.
| Parameter | Zulu Time | PhaseChecker |
|---|---|---|
| Price | $0.99 | $0.99 |
| Rating | 4.8 (2.6K ratings) — better | 2.0 (3 ratings) |
| Positive reviews | 78.6% of reviews — better | 15.8% of reviews |
| Number of ratings | 2.6K — better | 3 |
| Update frequency | Every 3 months — better | Every 43 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free — better | Paid |
| Best chart rank | #64 — better | — |
| Devices | iPhone, iPad, Apple Watch | iPhone, iPad, iPod |
| Requires iOS | 17.6 | 14.1 — better |
| Further details — not scored | ||
| Size | 16 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | Derek Spears | Rick Peacock |
Customer experience
Zulu Time
PhaseChecker
Bugs and requests
Zulu Time
Reported bugs
3 issues- Complication freezes after a few days
- Zulu time loses accuracy over time on Apple Watch
- Widget not updating local time properly
Requested features
5 requests- Add alarm feature
- Allow landscape mode for bedside clock view
- Provide option for always-on display
- Add time zone map for quick reference
- Show day of year in display
PhaseChecker
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Zulu Time
No in-app purchases
PhaseChecker
No in-app purchases









