You should definitely ask before you use another company’s logo on your site. While most companies won’t have a problem with this (especially since many deem this as additional marketing for them), you never know if they have restrictions or requirements when using their logo. The reality is, since they have likely trademarked the logo, then they control what happens with it. You don’t want to unintentionally put yourself into litigation over something that can easily be avoided.
If you’d like to learn more about trademark law, check out our website.is a marketplace of freelance attorneys, including those specialized in intellectual property. If you have more questions about the legality, get in touch for a consultation.