I have been following a listserve discussion about crediting your web designer with a link at the bottom of your web site template. This link then shows up on every page of your site. This was far more common in the 90s but you still see it now and then.
My opinion: In almost all cases it is wildly inappropriate.
Your organization’s web site is there to support and build your own brand and drive your web site visitors toward the actions you wish them to take online. It is not there to guide traffic to your designer.
These links to the designer are also much more valuable these days because Google will use them as an indicator to enhance the designer’s placement in natural search results. Links like this appear to me as, at best, amateurish or, at worst, an opportune grab at some Google link equity.
If you do allow this (you shouldn’t), it should be part of a deal that recognizes the huge value of the links to your design firm. Get a discount, get some free services, something. Also, if you use or adapt a free template, including the original designer’s link on it is appropriate.
If you want to acknowledge the designer who created your site for you, a good way to do so is by creating an ‘about this site’ page that provides a link to the design firm on that single page. This gives acknowledgement for a good job done without pasting the link inappropriately across your entire site.