Adding Check-The-Sum

Adding Check-The-Sum

README.md

@@ -1149,6 +1149,7 @@ Enter two images and the difference will show up below
 - [Punkspider](https://punkspider.org/) - Searching for vulnerable websites is coming back soon! Are you new to web security and have no idea what the heck we're talking about
 - [metabigor](https://github.com/j3ssie/metabigor) - OSINT tools and more but without API key
 - [urldna](https://urldna.io) - Gather info about URL: ssl cert, ip, header, metadat ...
+- [Check-The-Sum](https://check-the-sum.fr/) - Database of IP addresses, domains and malicious files collected from a network of honeypots
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