It's a good extension, it works, but the whitelist feature doesn't seem to. I use Windscribe VPN and they offer their users the option to mine Monero for them (using Coin-Hive) and upgrade to pro for a month, add 10GB of bandwidth permanently, and reset your bandwidth for the month. I really like this and use it all the time, but when I try to permanently whitelist windscribe.com and refresh the page, it isn't whitelisted any more. This is a huge issue for me and I won't be using the extension unless this is fixed. If you want an add-on that blocks mining everywhere period, this is perfect for you; it's just not for me.

If you want to look at the Windscribe page to see what I'm talking about, here is a link:

windscribe.com/miner/gamvw4hc

This is my link; if you visit the page, up to 50% of you CPU will be used to mine Monero and it will be added to my account (if you do, thank you!). If you don't want this, I think you can visit windscribe.com/miner and you'll be able to view the page. It'll still mine with your CPU, it just wouldn't be accredited to anyone's account; it'll all go to Windscribe with no user-benefit.

It really needs some improvements to allow captcha's to work.