Comment by shevy-java

In the US, there are several thousands of banks and credit unions, and the smaller ones use a patchwork of different vendor software. They likely don't have to write COBOL directly, but some of those components are still running it.

From the vendor's perspective, it doesn't make sense to do a complete rewrite and risk creating hairy financial issues for potentially hundreds of clients.

As others have said, US banks seem to run a lot of it, as in they have millions of lines of code of it.

This is not saying that banks don't also have a metric shitload of Java, they do. I think most people would be surprised how much code your average large bank manages.

I'm in Australia and a friend of a friend had a COBOL job working at a mid-sized bank (the COBOL had lots of Java on top). Australia's big banks are older than this bank so if they're not using COBOL at the bottom layer, they'll be using something similarly old for sure.

ECB is mostly COBOL and Fortran. The interfaces are Java, but not the backend.