Take it like a gift
differer
differer finds how URLs are parsed by different languages in order to help bug hunters break filters.
CloudFail
Utilize misconfigured DNS and old database records to find hidden IPs behind CloudFlare network.
DNSProbe
Allows you to perform multiple dns queries of your choice with a list of user supplied resolvers.
HTTP Request Smuggler
Extension for Burp Suite designed to help you launch HTTP Request Smuggling attacks.
Dastardly Scan Action
Runs a scan using Dastardly by Burp Suite against a target site and generates a report.