For bitcoin there is Bitcoin Core which downloads the whole blockchain a few hundred gigabytes then you can use the wallet.
For Ethereum, there used to be a wallet. I have done a backup of the key stores but now I am trying to download that classic wallet but I can't find a download link.
The only nearest thing I found was MyEtherWallet (MEW) but then there is no Download button anywhere on their website, and even whien i try the software version it says Not recommended:
https://www.myetherwallet.com/access-my-walletAny help how to get access to a wallet using the backup keystores from the "old"/"classic" wallet?
Using myetherwallet why have to download file, you can access with private key only and you need put your private key data to log in on your account, I think its easy way how to access to myetherwallet and sell your fund, you can sell easily and not have to worry with file have to download.