Heart Rate Variability Logger lets you record, plot and export time, frequency and non-linear HRV Features (includes experience sampling, RR-interval correction, DFA alpha 1 for training intensity analysis with respect to the aerobic threshold (0.75) in real-time, comparison between recordings, activity monitoring & step counting, location tracking).

Heart Rate Variability Logger requires a Bluetooth Low Energy (also called Bluetooth Smart or BLE or 4.0) heart rate sensor (we recommend Polar H7 or H10)

Main features:
- Extracts, plots, stores and exports heart rate, rr-intervals, time and frequency domain heart rate variability features (AVNN, SDNN, rMSSD, pNN50, LF, HF, LF/HF, alpha 1 from DFA)
- Configurable time window for features computation (choose between 30 seconds, 1, 2 or 5 minutes)
- RR-intervals correction can be enabled to prevent ectopic beats or artifacts from affecting HRV features
- Filters data based on the selected threshold
- Data export using email or Dropbox

More information, here: https://www.hrv.tools/hrv-logger-faq.html