Anyone who deals with cryptocurrencies knows that mining requires very powerful systems. So if you are thinking of pursuing a "sport" you must first invest in a very good computer system. 
Recently some websites have begun to use the resources of the user system they are visiting for mining. Some of them display a notification on the screen that explains what happens before they start, while others start using your system without saying anything.
This publication refers to the second sites, which are starting to use the resources of their visitors' systems to gain cryprobes.
Who is mining? is a web application that has a comprehensive list of all known mining websites. It also allows you to check out a mining page without telling it to the end user.
Visit it whoismining.com and enter the URL of the page you suspect is using it browser you to do cryptocurrency mining. The web application will confirm if your suspicions are true.
The app still has endless lists of webpages with that behavior.
If you see that a page you are interested in uses the computer you, you can simply stop visiting it. If you still can't do without it you can block mining from your browser with one additional or an extension.
It's worth debating whether or not this practice is right, especially when sites choose not to reveal what they're doing. Some users of these pages have no problem allowing their system to be used for mining crypto, however it should be up to the user whether they want to do so or not.
