What is the ruling on helping others in the field of computers and programming, whether by modifying a website that contains Sharia-prohibited content, or teaching programming information without knowing its use, or sending an application to someone who might use it for both lawful and unlawful purposes?

It is permissible to assist a person in modifying a website that offers permissible services. This is not forbidden due to the presence of some prohibitions, because the original assistance is for something permissible. However, enjoining good and forbidding evil is obligatory. It is also permissible to teach programming concepts without needing to inquire about how they will be used. Similarly, it is permissible to send permissible applications unless it is known or strongly presumed that their use will be for something forbidden.