Question Summary:
Working for software development used by conventional banks.

Question Detail:

WORKING FOR SOFTWARE DEVELOPMENT USED BY CONVETIONAL BANKS. Additional to fatwa 26052 i would like to know if its permissible working as a software developer in software devisions of commercial banks or other companies who develop softwares for commercial banks.
These softwares would be used to provide various functionalities of a conventional bank to users online.
Also other than this there could be other uses of this software e.g bathc processing of new account opening applications, checking of credit historry for a new customer for providing him loans etc.

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
Your sensitivity to earning a halal income is commendable. Earning a halal income invokes the mercy of Allah Ta’āla and barakah in one's wealth.
Since software development itself does not entail any haram action and in particular the software in reference provides multiple functions, some of which are permissible, your income will be halal and it will be permissible for you to pursue this job.[1]
 
And Allah Ta’āla Knows Best
Bilal Mohammad
Student Darul Iftaa
New Jersey, USA 
Checked and Approved by,
Mufti Ebrahim Desai.
www.daruliftaa.net