x64dbg (https://x64dbg.com) is an open source debugger. You can use x64dbg to debug both 32-bit and 64-bit applications. It has an easy-to-use GUI and offers various debugging features (https://x64dbg.com/#features).
In this section, you will see some of the debugging features offered by x64dbg, and how to use it to debug a malicious binary.