Tanpura helps with Shadaj and Pancham. It is difficult to check our swaras.
https://youtu.be/r-e972xgsZA please look at this other raga darshan videos in the playlist to visualise nuances and intricacies bansuri vadan of Pt. Rakesh Chaurasia and other vocalists. You can see all detailing with shruti.
I use this too. Called shruti. There is a hindustani version also of same name based on 22shruti principle
@vinodt1347 there is Shruti Carnatic Tuner by Kuyil the carnatic app. The hindustani one is just shruti tuner by prashant punde. I find the former better. I don't think there are exact standards in any Indian tuning
There is an app called Carnatic Tuner, which I use to check if my vocal notes are in the correct sur. I believe this is used for tuning the Carnatic flute, but I find it useful as a Hindustani vocal learner, as it provides all scales and a complete set of 12 strutis.
What you refer to for practicing the swara on any instrument ( or vocal), is the tanpura. The tanpura gives out many of the swaras of the saptak as part of its harmonics, and is hence the best reference for the natural scale...
While there are many apps available for tanpura, the itablapro app for IOS is quite popular..