I downloaded a free app on my phone called 'Cello Coach'.
It is really simple and made me realise how bad my intonation actually is after months of wallowing in the glory of self-satisfaction.
Such is the life of a string player.
If you use it do not get too wrapped up in the exactness of pure pitch as that is foolhardy. Also, I am not convinced it is always accurate. But it does bring up mistakes that you make a lot so can act on them.
I have small hands, also a bit of arthritis, so I avoid first position at all costs. As I am teaching again I really need to be good in first position so this app, by Jonathan Humphries, is a really useful tool. It also has a tuner which is great in itself and better than my other old one.
We are not looking to sound like a machine or a robot.
However, it is so useful for practicing, especially extensions.
Do not pay too much attention to percentages as it doesn't make much sense if you do and you can end up playing worse.....trust your ear and heart and then the machine. I t can't measure vibrato for example.
It keeps a record of supposed improvement, although, I got steadily worse the more I tried to match it. As with all my recommendations, use sparingly as another string to your bow....see what I did there?...Drone....oh and again!
Ok, I am off to nurse my ego.