Apache JMeter - Apache JMeter™.
Postman - The Collaboration Platform for API Development
Selenium - Selenium automates browsers. That's it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that.
TablePlus for Windows - A native GUI tool for MySQL, PostgreSQL, SQL Server & more
TestRail - TestRail provides comprehensive test case management for software testing. Organize your testing, boost productivity, get real-time insights, and track progress toward milestones. Integrates with leading issue tracking and test automation tools.
API List - A collective list of APIs. Build something.