This might help, Monzo published a blog detailing their technology stack a while ago -
https://monzo.com/blog/2016/09/19/building-a-modern-bank-bac...
https://monzo.com/blog/2016/09/19/building-a-modern-bank-bac...
I just wanna add that I think it's beyond cool that there's a bank out there that's publishing a dev blog and detailing their tech stack.