Making a program which will be used for halaal and haraam
Question

                I want to design a web-site for a company, or make a computer program for them. I know that some of the things that this company does are halaal, and some are haraam.

Is it permissible for me to do this, knowing that I myself will not be directly involved in doing the haraam things? All I will be doing is preparing the program or designing the web-site, which they will use in their work.
Praise be to Allah.We
      put this question to Shaykh Muhammad ibn Saalih al-‘Uthaymeen,who replied as follows: 
If most of the work which this company does is haraam,
      then it is not permissible for him to do that. If most of what they do is
      permitted, then it is permissible for him to do it. If they (haraam and
      halaal elements) are the same, then he should not do it, on the assumption
      that what is haraam will outweigh what is halaal. And Allaah knows best.