WordPress is the world's most popular content management system (CMS). You basically can't browse the internet without stumbling across a WordPress site. TechCrunch, Wired, People.com, the Yelp Blog, and millions of other sites use WordPress.
One of the reasons why WordPress is so popular is because, with all its themes and plugins, there are countless ways to customize your site. If you happen to see a theme or plugin you like, you might want to find out the name of the theme/plugin so that you can use it yourself.
Here's how to determine which theme or plugin a WordPress site is using:
How To Tell If A Site Was Made With WordPress
First, you need to know if the site you're on has been created with WordPress. Sometimes, you can find this information in the footer. If you don't see any mention of WordPress there, open the source code of the page (press CTRL + U) and search the text (CTRL + F) for "wp-content".
The page you're looking at right now is on a WordPress site. Follow the instructions above, and you'll find instances of "wp-content" in the source code that confirms this fact.
The Best Tools For Detecting Templates and Plugins
Individual site reports are always free. Built With offers more comprehensive web analysis plans that start at $295/month.
W3Techs is similar to Built With because it gives you a lot of data about a site. Its design is less flashy than Built With, but its reports are packed with information. W3Techs even gives you a "Technology Score" that measures the popularity (how many sites use the same technologies) and traffic (how much traffic other sites have received with the same technologies) for all the technologies used on the site. The term "technologies" is referring to content management service, social widgets, web servers, etc.
This tool also teaches you more about the CMS market as a whole. For example, a look at the W3Techs homepage will show you that, as of October 2017, WordPress has a CMS market share of 59.7%, while Joomla is at second-place with a 6.7% share and Drupal takes third with 4.7%.
At first, the CMS Detector will only show you which CMS the website is using. When you select "Click here to analyze fully", you'll get an in-depth report about the website. It gives you more information than WhatCMS, but less than BuiltWith or W3Techs.
What WordPress Theme Is That? is more involved than the rest of the entries on this list - it sends you directly to the WordPress plugin repository, so you can download the plugins for your own site immediately.