Burp or Burp Suite is a set of tools used for penetration testing of web applications. It is developed by a company named Portswigger who make freely available a Web Security Academy which has a range of lessons on penetration testing.

Monitor network requests and API failures with real-time insights

API Testing Platform that automatically generates unit test cases with dependency mocks from API calls

Design, debug, and test APIs locally or in the cloud

Uptime Kuma is an easy-to-use self-hosted monitoring tool.

Datadog is a cloud-based monitoring and analytics platform that provides observability and security for cloud-scale applications