Chinese Pronunciation App I am curious whether there is some good app or a website for practicing pronunciation of Chinese tones.
There is a way to practice pronunciation on HelloChinese but I find the tone recognition quite inaccurate. For instance, I can say an entire sentence with the same tone, which is clearly wrong, and still the app would show half of the tones as correctly pronounced.
I highly doubt it's a good idea to rely on such apps. Try to mimic high quality recordings or even record yourself for comparison purposes.

Forvo is good for words and phrases, textbooks with an audio CD like Integrated Chinese, Učebnice čínské konverzace and such for whole sentences.

You can also try if some machine translators will get what you're saying by voice, but only for the lulz.