However, now there is a convenient way without unnecessary problems.
Enter your wallet number and select the exchanges you are interested in.
The list has: EtherDelta (ForkDelta), IDEX, Token store, Switcheo, Joyso, Enclaves, SingularX, EtherC, Decentrex, DEXY.
Here the link:
https://deltabalances.github.io
In my opinion, if the exchange must enter the private key is not safe. for example Etherdelta. I once lost my token on the exchange because my wallet address was hacked. thus they can freely take our assets in etherdelta just by entering the private key.