I originally gave this a bad review and I almost sent the card back. But after 2 months, I have mostly changed my mind. I'm leaving my old review below, but here is a new perspective and 3 more stars, for 4 stars total.

I had no trouble installing this or using it many many times afterwards. It has worked, as far as I can tell, exactly as CapitalOne wants it to work. It was different from my Bank of America Shop Safe, so at first I hated it. But I have found a way to use it well. It has a drawback I will describe, but in some ways its also better. Here is how I use it.
1. Keep the extension disabled, except when you need a new virtual credit card number. That way it cannot spy on you at every website you go to. When you need one, enable it, get the virtual card number and record it in your password vault. Disable the extension. The only problem here is that you must have a website open to "attach" the virtual number to. I have been able to occasionally get a number that is not yet attached to a site, but I cannot repeat it. When I can, I will add that info here. But you are not actually limited to that website. You can even use the number over the phone. It appears that the number is permanently attached to the first credit processor that uses it, like ShopSafe was. This is very useful, because giving number over the phone to a human is much more dangerous than typing it into a computer. (CapitalOne - Please support getting numbers that are independent of a website!! Thanks!)

Your charge goes pending at first, so you cannot delete virtual card right away. But every time you get a new one, check for old ones that you can delete. This was my substitute for being able to define an expiration date in ShopSafe. Its not automatic, and you cannot set a maximum charge amount, but it seems good enough. That said, I decided I did not actually have to delete them every time. As long as I knew who I gave it to, if I got any bogus charges, I would know where the problem was. And since the number is probably locked to the first card processor that uses it, it is unlikely that it could be used by anyone who stole it in an IT breach from a company where I used it. I could probably have done this with ShopSafe too, but didnt realize it. Now I feel comfortable using it for recurring charges also.

So...I am pretty happy right now. If I stopped being able to use a number over the phone, I would probably go looking for another credit card to replace this. Using it over the phone is not officially supported and this is the main reason I only have it 4 stars. The other reason is that I have to enable and disable it every time I use it. But thats not too onerous. Thanks Capital One! Sorry for the misunderstanding at first....

*********** ORIGINAL REVIEW ***********
If you are looking for a ShopSafe replacement (recently cancelled by Bank of America) Eno based virtual credit card numbers from a CapitalOne card are not for you. These virtual credit card numbers do not give you the same protections from online fraud and do not work the way you would expect. First, you must use this app to create and manage virtual numbers. There is no website that I can find. This app is "always on" and watching your browsing activity to look for a site it thinks you might want a virtual credit card number for. So your browsing activity is no longer private. You cannot create a virtual card number until the app sees you on such a site. I was able to activate it on a dummy site, but then it links that URL to the credit card number. It set the expiration date of the virtual credit card 5 years into the future, oddly, past the expiration date for my real Capital One credit card. You cannot set a virtual number to expire after a certain number of months, like you could for ShopSafe numbers. Likewise, you cannot set a maximum charge amount for a virtual number, so anyone who gets this can charge as much as they like. So Eno virtual credit card numbers don't protect you from an unscrupulous online vendor, like ShopSafe did. In fact, if you read the Terms and Conditions, you will see that the virtual number may not even be locked to a specific merchant, like ShopSafe was. They appear to be testing this, but "...a VC# you create for use Merchant A should work at Merchant A, but may or may not work at Merchant B." So in my opinion, this does not really protect me very much. In fact, since there are no limits on the merchants and you cannot limit the maximum amount nor set a short expiration date, it may make you more vulnerable to fraud. If someone steals a virtual number from a company you gave it to, they can use it just as if they stole a card from your wallet. The only reasonable thing you can really do is delete the virtual number, but that assumes you know it was stolen. We usually dont find out about that until long long after it happens.

In fairness, unlike other reviews, I will say that I had no problems using my phone number to validate (via text messages) and get this set up. Setup worked just fine.

I am thinking carefully, because I really want a ShopSafe alternative, but this credit card will probably go back.