Edit: multi domain assets would be nice. Many applications suggested here have only simple flowchart + UML diagrams.

Draw.io is pretty good. It has a desktop version you can download as Flatpak. I even use it at work and got the IT dept. to install it by default. They're saving hundreds a month due to this.

Draw.io my feeling is you you need anything more fancy, you have missed the point of flowcharts and things like it. I have used the basic tools in libre office and word, it just depends on what you need to do.

Wait, has that become open source again in recent releases? I remember it not being for a while, but the repo currently says Apache 2.0? Anyone know more about it?

This

I think this quote says enough:

The icon sets and stencil libraries included in this software, and any derivatives thereof (including conversions to other formats, traced reproductions, substantially similar visual representations, or AI-generated images created using these icons as reference or training input), may not be used as software assets in, distributed for use with, or incorporated into Atlassian products or products distributed through the Atlassian marketplace or plugin ecosystem, without explicit written permission.

Do you prefer to code your diagrams? Many options to see and try at:

https://kroki.io/

Pikchr is surprisingly quick to get results in.

LibreOffice Draw worked well enough for me. It can even open Visio documents. It doesn't save to Visio though, so I had to give up on it eventually as the company mandated Visio documents, even though they just end up being inserted into other documents as PNG.

But the drawing part was solid for me.

Plus its just XML to its easy to derive flows programically

And you can export to PNG with the source XML embedded in the PNG metadata, effectively making it an editable PNG

I love yEd graph editor because you can import your own assets and make it like Visio.

I like drawdb.app.

What the what?!? I need to know more

I was looking for one of these yesterday and honestly they're all pretty clunky web browser applets. If I'm replacing a Microsoft Office program I want a fully featured desktop app, not a .io website, yknow?

I personally used latex with the tikz library.. It was strange but all the other things annoyed me

I detest the differences in their desktop and online versions. Office is such a cumbersome mess.

Visio online is useless, just a viewer.

Well yeah. If i wanted to use a browser applet, I don't see why I'd use MS at all. But for this specific use case (diagramming and flowcharting), Visio (imo) is pretty far ahead of LibreOffice Draw and that's the only serious offline non-MS option for this.

I think I've used this as well. I like how they have plantUML as well

EXCALIDRAW!!!!!

LOVE, LOVE LOVE EXCALIDRAW!

Sorry, caps, but, I really do love it that much. And it's just right there on the web, free, you can load it up on any computer and illustrate any concept. LOVE it.

I've used it for everything from a quick sketch during a brainstorming session, to highly complex network diagrams that wind up embedded in 'official' docs in Confluence and such, which would traditionally be the realm of Visio in my line of work. I love it so so so much - and am not in any way affiliated, lol, just a very passionate user!

I quite like mermaid.js for fast flowcharts. It's intuitive enough and works in a fair few markdown programs too. Wouldn't recommend it as a full Visio replacement, but it's good enough for 90% of my needs.

I have a chip on my shoulder, if office is mentioned I have to make sure everyone hates it

I'm a big fan, its just such a great open source tool and it comes with full BPMN2.0 support out of the box.

Mermaid.js and UML has covered what I thought were some pretty complex systems diagrams myself

I also need to know more, that's an amazing feature