Use this functionality in a completely offline app on an isolated device for $16.99 (PC), iOS AppStore or Google Play Store.
Convert Bitcoin (BTC) WIF to private key 
Where you have generated or been issued a private key for Bitcoin and its technological analogues (i.e. Bitcoin forks: Bitcoin cash, Dogecoin, etc.), you may have received the private key in a special WIF format (Wallet Import Format). However, not every wallet accepts both formats (usually either WIF or standard), so here you can convert it to a regular private key or vice versa.
It is advisable to switch off the internet now, convert, close this tab and only then switch on the internet.
This page can work 100% offline.
Your classic private key:
You can use this functionality for these coins as well:
Bitcoin Cash (BCH)
Bitcoin SV (BSV)
eCash (XEC)
Bitcoin Gold (BTG)
Litecoin (LTC)
Dogecoin (DOGE)
And also for any other if you know that it is built on Bitcoin technology.
Bitcoin Cash (BCH)
Bitcoin SV (BSV)
eCash (XEC)
Bitcoin Gold (BTG)
Litecoin (LTC)
Dogecoin (DOGE)
And also for any other if you know that it is built on Bitcoin technology.