Of course is it safe, but you also need to use 2FA your exchange account before use third party program.
Anything has it risk, so i made the risk lower by using 2FA on my bittrex account
that is true , anything online shouldn't be trusted 100% especially a third party that not well known, people must aware about this. a 2 FA must set in every single digital asset you have , otherwise you have to feel insecure all day long .
i have no big deal with Z Trader since long time ago , all smooth , my fund secured as i always use 2FA.