KD Serials vs Four
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
KD Serials
Read full descriptionHide full description
KD series volt-ampere meter is a new type of coulomb meter that can measure various physical parameters such as voltage, current, power, charge and discharge capacity, remaining time, etc. At the same time, parameters can also be set to achieve full capacity voltage, zero capacity voltage, low capacity alarms, etc. Features. The meter can automatically identify the direction of the current, and can monitor the battery capacity in real time and use a broken code liquid crystal display. The measured data display information is comprehensive and user-friendly.
Four
Read full descriptionHide full description
1. After logging in to the APP, you can simultaneously view the devices installed in the sensor cloud platform; 2. After the account obtains the corresponding permissions, it can edit and delete the installed equipment and other management operations; 3. After switching the video device, you can view, play back and capture the installed video device in real time; 4. When the device has an alarm, the alarm will be displayed in the device alarm column, and it will also be pushed to the mobile phone through the message; 5.The APP also provides functions such as notification announcement, message setting, language setting, beginner's guide, and personal information editing.
Screenshots
Verdict
The clearest difference is update cadence: KD Serials at every 4 weeks against Four's every 2 months. KD Serials also leads on iOS requirement (9.0 vs 12.0). 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
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
KD Serials ships an update every 4 weeks, Four every 2 months. The most recent releases landed on October 1, 2026 and October 14, 2026 respectively.
| Parameter | KD Serials | Four |
|---|---|---|
| Price | Free | Free |
| Update frequency | Every 4 weeks — better | Every 2 months |
| Ads | No | No |
| In-app purchases | No | No |
| Devices | iPhone, iPod | iPhone, iPad, iPod — better |
| Requires iOS | 9.0 — better | 12.0 |
| Further details — not scored | ||
| Size | 39 MB | 58 MB |
| Age rating | 4+ | 17+ |
| Developer | Hangzhou Junce Instruments Co., Ltd. | Xiamen Sixin IoT Technology Co., Ltd. |
In-app purchases
KD Serials
No in-app purchases
Four
No in-app purchases









