Chronometer vs Blue Light Filter
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Chronometer
Easily track your watch's accuracy against atomic time. Simply set your watch to atomic time, take a photo of the dial within the app, and record the difference. Analyze daily deviations over 15 days to assess your watch's performance.
- Track daily watch accuracy
- Compare against atomic time
- Photo capture for time reading
- Altitude recording
- Save data in CSV format
- Analyze 15-day data trends
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Chronometer – Mechanical Watch Accuracy This app helps you track the real-world accuracy and long-term rate performance of your mechanical watch. It provides an easy way to measure the daily rate of your watch against an accurate NTP time reference and to follow its performance over days, weeks or months. Before starting a new measurement series, synchronize your watch with an accurate time reference. Do not reset the watch during the measurement period. An internet connection is required to obtain the precise NTP reference time. How to measure your watch 1. Start the app and wait until the NTP server has synchronized. The NTP time turns green when the reference time is available. 2. Point the camera at the watch dial. You can use pinch-to-zoom and, on supported devices, the macro capability for precise reading of the seconds hand. 3. Tap the camera button to freeze the image. The app records the corresponding NTP reference time. 4. Read the exact time from the frozen image and adjust the displayed watch time using the picker wheels. 5. If desired, enter the current altitude above sea level. 6. Tap Save Rate to store the measurement. 7. Tap the camera button again to return to the live camera view. For the best results, measure your watch once per day at approximately the same time. If more than one day passes between two measurements, the app automatically calculates the average daily rate for that interval. Performance evaluation The graph shows the daily rate of your watch together with the standard COSC limits and the more demanding COSC Excellence limits. After at least 15 measurements, the app provides an additional COSC Evaluation based on the most recent 15 daily rate values. The evaluation includes a COSC pass/fail assessment and a Concours Score from 0 to 500 points, derived from the chronometer competition formula. The Concours Score does not include the thermal coefficient (CT). Temperature testing, controlled positional changes, magnetic exposure and shock testing cannot be reproduced during normal everyday use. The result is therefore not an official COSC certification, but a practical evaluation of the real-world rate performance of your watch. The complete measurement history can be exported as a CSV file for further analysis. The exported data includes the date, absolute rate difference, daily rate difference and altitude above sea level. Time reference: Swiss NTP server ntp11.metas.ch The app also includes a COSC NTP 4 Hz reference dial for calibration and verification of optical timing instruments. Requires iOS 18.6 or later.
Blue Light Filter
Reduce eye strain and improve sleep with an adjustable blue light filter. Organize your files, photos, and videos with an integrated file manager. Enjoy a seamless web browsing experience with built-in filtering and bookmarking.
- Adjustable blue light filter
- Eye strain relief
- Improved sleep quality
- Intuitive file manager
- Zip/unzip support
- Integrated web browser
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Blue Light Filter is your all-in-one solution for a comfortable and productive digital experience on iOS. Equip your device with our adjustable blue light filter to alleviate eye strain and improve sleep quality, especially during nighttime browsing and reading. Effortlessly manage and organize your documents, photos, and videos with our intuitive file manager, featuring zip/unzip support. Enjoy a seamless web browsing experience with an integrated blue light filter and easy access to bookmarks and history. Designed with a user-friendly interface, the app ensures easy navigation for users of all ages, and is fully optimized for iOS with Dark Mode compatibility, haptic feedback, and quick actions via 3D Touch. Download Blue Light Filter today and transform your screen time into a safer, more comfortable, and more efficient experience. Privacy Policy: https://riviacorp.com/privacy-filter/ Terms of Services: https://riviacorp.com/terms-filter/ Support: https://riviacorp.com/
Screenshots
Verdict
The clearest difference is price: Blue Light Filter at Free against Chronometer's $2.99. Blue Light Filter also leads on update cadence (weekly vs every 5 months) and ratings volume (137 vs 8). Chronometer's advantage is in-app purchases (none vs 5). On rating, review sentiment, ads 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
Blue Light Filter is free to download; Chronometer costs $2.99 up front. Blue Light Filter sells 5 in-app purchases, starting at $4.99 per 7 days. Chronometer asks for nothing beyond the download.
Blue Light Filter holds the better App Store score, 3.3 against 3.1. That said, the two scores are not equally well evidenced: Blue Light Filter has 137 ratings behind it against 8, so its average is the more settled of the two. Written reviews point the same way: 0% of Chronometer's written reviews are positive against 3% of Blue Light Filter's.
Chronometer ships an update every 5 months, Blue Light Filter weekly. The most recent releases landed on October 8, 2026 and October 13, 2026 respectively.
| Parameter | Chronometer | Blue Light Filter |
|---|---|---|
| Price | $2.99 | Free — better |
| Rating | 3.1 (8 ratings) | 3.3 (137 ratings) — better |
| Positive reviews | 0.0% of reviews | 2.6% of reviews — better |
| Number of ratings | 8 | 137 — better |
| Update frequency | Every 5 months | Weekly — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Paid | Free with in-app purchases — better |
| Devices | iPhone, iPad | iPhone, iPad, Mac — better |
| Requires iOS | 18.6 | 17.0 — better |
| Further details — not scored | ||
| Size | 3 MB | 19 MB |
| Age rating | 4+ | 17+ |
| Developer | Kilian Eisenegger | Rivia Corp s.r.o. |
Customer experience
Chronometer
Blue Light Filter
In-app purchases
Chronometer
No in-app purchases
Blue Light Filter
- Weekly3 Days trial$4.997 Days
- 1 month3 Days trial$6.991 Month
- Blue Light Filter - Monthly3 Days trial$7.991 Month
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- 1 year3 Days trial$24.991 Year
- Annually$29.991 Year
Questions
Is Chronometer free?
Is Blue Light Filter free?
Which has better reviews, Chronometer or Blue Light Filter?
Do Chronometer or Blue Light Filter have ads?
Which is updated more often, Chronometer or Blue Light Filter?
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