If you're in the UK, EU, New Zealand, Australia, or Singapore, I found out yesterday that Wise (TransferWise) customers get 3 virtual cards free of charge [1][2].

I'd be interested to hear about any other UK/EU firms offering similar.

[1] https://wise.com/gb/blog/shop-safely-virtually-anywhere

[2] https://news.ycombinator.com/item?id=27006326

Revolut supports one time cards... provided you're happy with Revolut.