What Tandem is doing better that HelloTalk:

Tandem

+ has full web version of their app
+ allows 8 languages for free (instead of only one language in HelloTalk)
+ voice messages are not only 60 seconds long like at HelloTalk (HelloTalk allows only 60 seconds long voice messages, which is a shame)

What HelloTalk is doing better than Tandem:

+ way better functionality; there are many useful features such as:

• deleteable messages (!!!)
• one can quote-reply to ALL messages (!!!)

and many others … If you’d like to know which exactly – ask me.

I regularly submit new features to HelloTalk; let’s see if they will implement any of them.
If they do, I’ll feel happier.