I use an offline wallet (myetherwallet), as they say.
Recently many online platform got hacked
Hacked or ran away with their user's money Recently many online platform got hacked
Anyway, OP would be better to use Electrum instead, maybe Bitcoin Core if he has the bandwith to download all the data.
Keep the private key and seed safe, nothing can steal your coins now, unless your PC has virus, which in this case is in user's blame.