Wordpress Theme Finder ToolWorldpress Theme Finder Tool
Which WordPress topic is this? What WordPress Theme Is That was established in 2011 and is one of the longest run and most loved WordPress discovery tool. Recognising both topics and plug-ins (although, like any of these tools: the number of plug-ins it can recognise is extremely limited), the tool is unbelievably fast and simple to use, but often gives a little less information than some of its competitors (especially in relation to topic specifics).
Catalin Zorzini (the man behind the beloved web magazine Inspired Magazine) has developed What Theme, a relatively new theme recognition tool that has the benefit of recognising not only WordPress topics, but also Drupal, Joomla and Ghost topics (and a few others). Wonderful for complete ease perhaps, but if you're looking for more than the most apparent detail about which particular topic a website uses, I would suggest to compare the results of that particular tool with those of another.
The ones who use chromes may be happy to try: Besides working directly within Chromes (it's a Chromes expansion that, after installation, places a convenient sniffer symbol in the upper right corner of the browsers bar for ease of access), this special tool also summarizes the results of its sniffers in a website so people can see how often it has recognized a particular topic.
For example, at the point of typing, the page shows information that says it has been used 76,581 times and has recognized over 22,000 WordPress topics - the most beloved of which is Avada. Bonus tool: Though not a tool for recognizing WordPress topics, there is also another practical WordPress enhancement that is definitely Worth trying (for those who might be interested):
And if everything else goes wrong, keep in mind that there's always a more overall personal way to just send an email to the website in query to ask if it's lucky/willing to tell you a little bit more about the theme used and/or the overall look of its website (damn it, you might even be delighted that you're so interested)!