Where can I find a nice background abstract shape generator ?

For example, versoly.com has this nice background shape: https://s3.amazonaws.com/versoly/images/dafc1e05-b0e8-4c6d-b375-4a62333bbd5a/8a27fdce-65e5-40f0-b94d-9b65f4f36a12.png

And there is an abstract background shape in the design a kind Indie Hacker did for me: https://imgur.com/DLW3GGN

I asked Versoly's founders, but they don't remember what the tool they used was and I searched for quite some time after that on Google: did not find the tool or a similar one.

Does anyone know ?