Here's the thing, some webmasters will bounce their code between a number of programs using different ones for how easily they perform a certain task. This is done in much the same way that some graphic artists will open a graphic in multiple programs for their ease of use.
I realize you're mostly looking for a basic idea, but I just wanted to point out that there is not always easily identifiable trace code for a specific program. This may be another reason BuiltWith could be easily fooled. Still, it's good to have another tool in the tool belt. Thanks for sharing.