SensorLog vs OpenPPG
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
SensorLog
Record and stream sensor data from your iPhone, iPad, and Apple Watch. Export data in CSV or JSON format, or send it via TCP, UDP, or HTTP requests. Integrates with Core ML models for advanced analysis.
- Log sensor data up to 100Hz
- Stream data via TCP/UDP or HTTP
- Export data as CSV or JSON
- Remote client/server functionality
- Siri and Shortcuts integration
- Core ML model support
- HealthKit data export from Apple Watch
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With SensorLog you can read sensor data from the iPhone, iPad and Apple Watch. The sensor data can be saved as a file in CSV or JSON format, streamed via TCP/UDP or sent as an HTTP request. The most important functions for iPhone and iPad: - Sensor data can be recorded at up to 100Hz (depending on the iOS device version and sensor type). - Sensor data can be streamed in server or client mode using TCP or UDP. Depending on the network speed and the server or client configuration used, this is possible with up to 100Hz. - Via HTTP(S) GET/POST request, sensor data in JSON format (POST) or form-url encoded (POST and GET) can be transmitted to a REST API with up to 20Hz. - With the SensorLog Remote Client/Server function, an iPad or iPhone can connect as a SensorLog Remote Client to an iPhone or iPad, which takes on the role of SensorLog Remote Server. The client's sensor data can be visualized on the server, and the server can control the clients (start/stop logging, start/stop sending data). - Logging can be started and stopped using Siri and shortcuts. - SensorLog supports Core ML models created with Apple's Create ML app. Log data with SensorLog, train a model with the data in Create ML, load exported models in SensorLog and log the model prediction. Supported Create ML models are: Activity Classifier, Tabular Regressor and Tabular Classifier. - If you have an Apple Watch, HealthKit data such as heart rate, energy used, sleep and movement data can be exported on the watch as a csv or json file and then transferred to your iPhone. Sensor data iPhone / iPad: For sample log files, please visit the SensorLog homepage (link App Support). - CLLocation, CLHeading, CMAccelerometer, CMGyroData, CMMagnetometer, CMDeviceMotion, CMActivity, CMPedometer, CMAltimeter, WLAN and network provider IP addresses, device orientation, battery info, decibels. The most important functions for Apple Watch: - Logging Option 1: Logging duration up to 1 hour Simultaneous logging of all selectable sensor data is supported in the background with up to 50Hz. Individual sensors can be logged with a higher frequency of up to 100Hz. Sending data via HTTP requests is supported. - Logging option 2: Logging duration greater than 1 hour In the background only logging of the accelerometer data with max. 50Hz is supported. In the foreground all sensor data with up to 100Hz. Sending data via HTTP requests is only supported when the app is in the foreground. - Via HTTP(S) GET/POST request, sensor data can be transmitted to a REST API with up to 10Hz in JSON format (POST) or form-url encoded (POST and GET). - The Health Store data feature off the SensorLog Watch app allows you to export HealthKit data like heart rate, energy burned, sleep, and movement data. This data is automatically recorded by your Watch and can be read out and exported by SensorLog as csv or json file and transferred to your iPhone. - Logging can be started and stopped using Siri and Shortcuts. Sensor Data Watch: For sample log files, please visit the SensorLog homepage (link App Support). - CLLocation, CMAccelerometer, CMDeviceMotion, CMActivity, CMPedometer, CMAltimeter, battery info
OpenPPG
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OpenPPG is a free, research-oriented iOS application designed to close the gap in accessible and transparent PPG data acquisition. Built by researchers for researchers, it enables recording of raw, high-quality photoplethysmography (PPG) signals directly from the smartphone camera, with full export for scientific analysis. Key Features • Raw signal access – capture unprocessed PPG waveforms with complete control over export (CSV format). • Flexible preprocessing – raw signals, basic and advanced filtering, signal quality assessment or fully calculated metrics in one app to enhance your research • Feature extraction – access directly over 11 automatically calculated temporal and morphological metrics without need for advanced signal processing • Metadata & annotations – mark events while taking measurements in real time and customise forms to fit your study protocol • Explainable pipeline – reproducible acquisition process with transparent documentation to ensure research reliability. Why OpenPPG? Most mobile tools restrict access to raw data, hide acquisition details, or require payment. OpenPPG removes these barriers by providing a free, standardised, and reproducible way to acquire PPG signals. It supports innovation in signal processing, machine learning, and digital biomarker discovery. Important: OpenPPG is intended solely for research purposes. It is not a medical device and must not be used for diagnosis, treatment, or patient self-monitoring.
Screenshots
Verdict
The clearest difference is price: OpenPPG at Free against SensorLog's $2.99. OpenPPG also leads on in-app purchases (none vs 4). SensorLog's advantage is chart position (#90 vs unranked) and device support (3 vs 1). On update cadence, ads and iOS requirement 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
OpenPPG is free to download; SensorLog costs $2.99 up front. SensorLog sells 4 one-off in-app purchases. OpenPPG asks for nothing beyond the download.
SensorLog ships an update every 2 months, OpenPPG monthly. The most recent releases landed on September 26, 2026 and September 24, 2026 respectively.
| Parameter | SensorLog | OpenPPG |
|---|---|---|
| Price | $2.99 | Free — better |
| Rating | 4.4 (40 ratings) — better | — |
| Positive reviews | 69.0% of reviews | — |
| Number of ratings | 40 — better | — |
| Update frequency | Every 2 months | Monthly — better |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | — |
| Best chart rank | #90 — better | — |
| Devices | iPhone, iPad, Apple Watch — better | iPhone |
| Requires iOS | 18.0 | 17.6 — better |
| Further details — not scored | ||
| Size | 4 MB | 9 MB |
| Age rating | 4+ | 4+ |
| Developer | Bernd Thomas | research app |
In-app purchases
SensorLog
- Buy me a Coffee ...$0.99
- Spend me an Ice Cream ...$1.99
- Offer me a glas of Wine ...$5.99
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- Invite me for a Cocktail ...$9.99
OpenPPG
No in-app purchases









