Working for a company that prepares software for banks
Q: I am a software engineer, currently working in a software house, I wanted to switch my job and later on I got a job in a very nice & reputable company. But they worked for banks, basically they are a banking solution provider, I know this thing from the very first day, but due to the lack of my knowledge, I was assuming that working in banks is impermissible and as I will not be going to work in a bank that's why I didn't bother. But when I got the offer letter, I did Istakhara. I did not see anything in my dream or I didn't get the clear picture of what I should do, then I searched on the Internet that what Islam says regarding this issue. I've found in many places that its forbidden to work
for bank or work for such companies who gain their profits from banks, so I refused.
I wanted to know that is it allowed in Islam to work for such companies that help banks? Keeping this in mind that I didn't know at the time of refusal that what kind of software they were requiring me to make.