What does our extension do?
When you're doing bug bounty hunting, sometimes you might want to perform some content enumeration on a website. This entails trying to find all the valid web pages on a certain part of the site. For example, if you see that users a referenced by a specific number in the URL, then you might want to find all the users of the website by plugging in different numbers for the "id" parameter. This tool makes it easier to enumerate users by not only automating the testing, but also by allowing you to input a custom error message to look for. If the program puts in an invalid user id, rather than throwing an error 404, sometimes a web site will send you to their own custom error page. By checking for this custom error message, this program knows to treat pages like that as "404"s as well.