Do I bear a sin if I point to a website for a program that blocks pornographic sites, knowing that the site contains pictures of unveiled women, and if the user looks at them, will I be sinful?

If there is a confirmed need for a useful program that can only be obtained by viewing images or listening to music, then it is permissible to commit these minor harms to achieve a greater benefit or ward off a greater corruption.

If the intended benefit of the programs outweighs the harms present in them, and the need for them is general, then there is no harm in guiding people to them, while cautioning them to avoid the harm if possible.

However, if there is no necessity or confirmed need, then there is no need to open such doors.