The Jantra App is meant to be used for High School, and University students, although any lab enthusiast will recognise it as a great tool to learn experiments.
As of February, 2021, it contains 3 fully featured tools of:
(1) Vernier Callipers
(2) Screw Gauge
(3) Spherometer

Note: All the models in this app is designed at Skaisys. However, you may use the graphics in your presentation or online tutorials, but with the name and link of the app provided in it.