For diagrams, Excalidraw (https://excalidraw.com https://excalidraw.com) is my favorite by a lot. Pretty low learning curve and you can use it as a single-playe

For diagrams, Excalidraw (https://excalidraw.com https://excalidraw.com) is my favorite by a lot. Pretty low learning curve and you can use it as a single-player as many times (you'll have to export the older file)