I use Draw.io for creating flowcharts and general image editing. It solves many problems for me, especially for dealing with customers, allowing me to create simple yet effective diagrams to explain a process. I like the ease of use and the vast selection of shapes, which let me effectively customize my projects. Whatever system I am designing, there's a sufficient range of shapes. Additionally, the initial setup was very easy.

The components are highly customizable and come with predefined diagrams, which helps you not have to start a diagram from scratch.

Its very easy to use and to collaborate with others.Also has Many templates that helps to make work easier and organized.