What it is: a speaking trainer for learners who understand more Mandarin than they can say. It teaches reusable chunks such as 我想问一下 and 在哪里, then gives you an English prompt that needs two or three of them, and you say the whole sentence out loud.

Why it's useful:

• It trains production, not recognition: you have to retrieve the chunks and say them, the way a real conversation demands.
• It checks which chunks you said and in what order, and scores your tones and pronunciation character by character, naming the tone you said against the tone the character wanted.
• Spaced repetition brings chunks back just before you would forget them, and you can add your own sentences to it.
• Content spans HSK 1 to 5, and a short placement starts you at your level.

Who it's for: learners who already know some Mandarin but freeze when they speak. It is not for absolute beginners.

What you need: a browser and a microphone (it works on a phone). It is paid: $30 a month after a 7-day free trial, and places open in small groups through a waiting list.

Disclosure: I'm one of the two people who built it.