Copyright of the studio that created the site — created by|in...?

Question

Copyright

A certain web studio [spherical in a vacuum] develops sites, how can it sign its work for several options:
1) The site was created from scratch on its own code (code + design + layout) - created by?
2) A site based on a spherical cms in a vacuum (that is, only design and layout) - design by | created in?
2.1) And if only the design was done, and the customer already did the layout -?
3) Only code created - CMS in fact - Powered by [studio_name]?

And in general, if it stands on the site in the footer “The site was created in the web studio BLA_BLA_BLA” (often found on the Internet) - this is how to logically understand - studio cms and design, or it is also signed by itself in the case of using joomla and some free theme then?

Answer 1

Why don't you want to speak Russian?:
- The site was created in the blah blah studio;
— Design created in blah blah studio;
Well, or just a link to the studio's website, without further ado.

Answer 2

I do not want to say that this is the ultimate truth, but it is worth reading this and this .
In general, I would recommend writing “With the support of [a spherical studio in a vacuum]”

Answer 3

created by - in this case, the studio itself is indicated (since we are talking about the artist who made the project)
created in - in this case, the toolkit (or development environment that was used to create the project) is indicated
powered by - in this case (as has already been correctly noticed) indicates the engine under which the project operates or indicates the person (for example, a web studio) that maintains the project or ensures its operation

Answer 4

Maybe just "With love from %studio%"... Very in the style of the themeforest authors...