tech-company, website, copyright, logoThere are many services or companies that display their technology stack on their website.
Proudly built with
[logo foo] [logo bar] [logo baz]
Many of the popular dev technologies are backed by business and even if they are open source, it does not automatically grant to use their name.
Do I really have to ask everyone for a permission to link to their tech in order to be legally safe?
Asking question to the project community will not do any harm and is probably the safest way to go. It may be that the question has already been asked and you only need to search. It may also be that the authors would not allow they logo on any crappy site but may allow on yours.
It is not true that most of the sites declare they technology stack, as providing such information is an additional security threat. Differently, a care if often made not to disclose the stack even indirectly (like inside the error messages).
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