I use draw.io at https://app.diagrams.net/

It is free and online. I can draw diagrams that I used to draw with Visio but I don't have to install software and can use it from anywhere.

I can export the documents to my local machine as a master file (e.g. file type is *.drawio) or can export them as an image (e.g. JPG, PNG, etc.)

There are lots of subjects that you can turn on (also free) ranging from architecture to electronics.

I can usually find what I need or something that works well enough for my simple needs.

I can also use it kinda like a white-board in screen-sharing meetings.

Though - looking at other comments - yEd looks pretty powerful. I'll have to check it out.

PlantUML [1] if you want to create diagrams with textual descriptions. I find that much easier to modify and maintain in the long run.

[1] https://plantuml.com/

I don't do a lot of diagramming...But I've found Yed[1] to be nice. Free & Cross Platform.

[1] https://www.yworks.com/products/yed

Plant text [1],

+ free + online no instalation needed + source is text file can be put in git for collaboration

- source is text file no drag&drop

[1] https://www.planttext.com/

Not a heavy UML user but the Dia Diagramming tool has worked well for me. Link: https://wiki.gnome.org/Apps/Dia

Check out Excalidraw - https://excalidraw.com/ It is an open source, no-frills tool that you can use to quickly draw simple diagrams.

I am using it quite often to sketch LoFi mocks.

It stores in your browser's localstorage, and you can easily collaborate with others in realtime.

I've seen Microsoft Visio used pretty often in larger/non-tech companies.

I opt for https://draw.io if I need a quick diagram personally (it's a big plus that you can guarantee the recipient has access since it can be opened from the browser version).

I’ve made mostly due with Google Doc with Google Drawings. They are editable, so better than a picture. However, the canvas has limited size, smaller than a doc page. It forces multiple drawings for a single flow sometimes.

We used to use Prezi. It is pretty amazing.

Pencil and paper or marker board. If you need share digitally, take a picture.

I need to collaborate with other people and because of COVID we are doing everything remote. Also modifications would be hard and time consuming with pencil and paper.

I learned uml in University couple of decades ago. I don't remember ever using UML since.

If you are using UML during design phase, you probably are not going in right direction.

first of all I would recommend to stay away from UML. It's a bloated tool. that don't translate to code.

for the design phase I think the C4model and a sequence diagram provide all the tools to think about your project.

in order to produce such diagrams you can use plantuml. Because that way you can store it with your code in git.

Lucidchart is a great option