What is the ruling on working as a software expert for a lending company that deals with usurious interest and other sources of income?

It is not permissible to work for companies that lend with usury (riba), as it is one of the gravest major sins. Allah has warned those who engage in it with war, as stated in His Almighty قول: "O you who have believed, fear Allah and give up what remains [due to you] of riba, if you should be believers. And if you do not, then be informed of a war [against you] from Allah and His Messenger. But if you repent, you may have your principal – [thus] you do no wrong, nor are you wronged." Working in such companies is considered aiding in forbidden usury. The Messenger of Allah, peace and blessings be upon him, cursed the one who consumes usury, the one who feeds it, its scribe, and its two witnesses, and he said: "They are all equal (in sin)."