Do you know any open-source and free (as in beer) mockup/wireframe tool for webdesign?

I may soon have two websites to build for little businesses, but I'd like to be able to create mockups for approval before diving into the code. As I was looking for tools, I was surprised to find no free and open-source software for the job. Everything is on a free trial model which I'd be glad to pay for if I had the money, but since I'm really just beginning, I'd rather use something free, and preferably open-source.

I'll use Gimp if nothing comes up, but since it's not intended for this kind of usage, it's a bit more time consuming to create something of quality on it.

Thanks a lot.

If you're on Windows 10, you can try Gravit Designer from Corel. It's not OS, but it's free.

I am not a designer, but the designers I've worked with have mostly used Figma for mocks and sketches. You need an account to use it, but from my limited experience it seems to work well enough.

Gravit works decently.

Try Figma, that's what I use. It's pretty cool.

Have you tried a Kellerbier?

You can use figma fir design a website... It's free and very easy to use..

Very basic one and free is pencil , available on linux

Figma 1000%

@24th-Dragon Unfortunately, it won't work on Linux, which I'm using.

@Solo-Coder, @PrivateGER : Seems very promising, has a web version and the desktop app works on Linux. The free version seems a bit limited (which is expected) but I'll keep an eye on it for the day I need a professionnal tool and am ready to spend money on it (50€/year is not expensive either).

@ltlian @neeno @itsVivek @jpl20 : Ok, I guess I'll have to try Figma, then, thanks a lot !

@M1sf3t draw.io is awesome, that was my second choice if nothing else came up. I know krita/inkscape, but I'd rather use Gimp as I'm more used to it.

@Ranchu I'm belgian. I tried one once, and didn't like it. I like my beers like I like my women : strong, manly, and intoxicating.

@balvinder294 I was expecting that comment, but honestly it's a bit hard to keep proportions constant, try different colors or move objects around with a pen and a paper. I'd use Gimp then :-).

@pipe The free version works pretty well for mockups. I never ran into a situation where I actually needed a Pro function. YMMV though.

@PrivateGER @M1sf3t : nice, I'll give it a spin then :-). I don't want to end up spending more time choosing a tool than using it, and I certainly don't need pro features, so I'm sure that Gravit or Figma will do the trick. I'll try them both on different projects to get the hang of them.

@pipe damn that's the Most organized reply i've ever read.

@pipe hahaha yeah I have tried mockup tools too, having the scale and rulers. But pencil looks pretty useful.
Thanks

@Ranchu Sadly, my replies may be the only thing I'm good at organizing. Even then, they're always too long.

@balvinder294 For quickly laying out ideas, it surely is the best tool, and I use it too at first. But should I need to show a more polished mockup to a client that believes only what they sees, I'd have to use a graphical tool.