What is Service fee
An exchanger's charge per trade on top of the rate, charged as a fixed amount, a percentage or both.
A service fee is deducted from the exchange amount. The fixed part weighs heavily on small trades: a 10,000 ₸ fee on a 50,000 ₸ purchase eats a fifth of the amount.
A no-fee exchanger is not necessarily cheaper, as its margin may sit in the spread. The Cryptokurs calculator accounts for both.