01 / Teaching simulator
Plethscape
Explore the anatomy behind a pulse signal. Compare sensor locations and wavelengths, then see how breathing and movement affect a simulated waveform.
The open lab
Interactive
PPG tools.
Change a parameter. Watch the waveform. Move from reading about optical signals to exploring how they behave.
02 / Open-source library · MIT
ppg-js
Build camera-based pulse experiments in the browser. Start with the phone demo, then explore the library, signal quality checks, and integration guides.
03 / Free calculators
Research and physiology calculators
Validated against R and Python reference implementations. Everything runs in your browser; your data is never uploaded.
- Wearable validation toolkitFree in-browser statistics for wearable validation studies: Bland-Altman limits with CIs, ICC, Cohen's kappa, MAE/MAPE and Lu 2016 sample size. Export figures and BibTeX.
- Bland–Altman calculator and plotFree Bland-Altman calculator: bias, 95% limits of agreement with confidence intervals, proportional bias test and a publication-ready plot (SVG/PNG). Runs in your browser.
- ICC calculatorFree intraclass correlation calculator. Get ICC(1,1), ICC(2,1), ICC(3,1) and the average-measure forms with McGraw-Wong confidence intervals and F tests, in your browser.
- Cohen's kappa calculatorFree Cohen's kappa calculator with linear and quadratic weighted kappa, 95% CI, z test and confusion matrix. Built for epoch-by-epoch sleep staging; runs in your browser.
- Bland–Altman sample size calculatorFree sample size calculator for method-comparison and wearable validation studies using the Lu et al. (2016) power method for Bland-Altman limits of agreement.
- SpO₂ at altitude checkerEnter your altitude to see the SpO2 range measured in healthy, acclimatised residents from 154 m to 5,100 m (Rojas-Camayo 2018), plus infant data. Free, private, educational.