cablop on "[Plugin: Contact Form 7] How to Enable Text field if option is not present in dropdown select?"

Yes, i'm looking for some conditional logic in the form.

Do you say it could be done via PHP + JavaScript coding? I'm PHP programmer and the API of WordPress is simple enough. Do you have any good pointers to give me on that topic?

I'll check Quform and Ninja Forms, Gravity Forms is too expensive for us just to be used on one or maybe two forms.