If you are an IT architect or specialist, you may have used PlantUML. I have and I really like it: It makes doing technical diagrams dead easy.
What I would like you to know about are non-UML capabilities of the tool. PlantUML has the capability to draw Gantt charts and Mindmaps. You can quickly write out your plans and ideas and PlantUML will convert them into the diagram you want. It’s fantastic and I highly recommend it. If you use Visual Studio Code from Microsoft, plug PlantUML into it and you can get your diagrams made that way. But the PlantUML website can also do the job.