Do you use Bootstrap?

Nope , I am not using Bootstrap anymore and I don't think I will be going back anytime soon.

Reason:Because most Bootstrap sites look really cookie-cutter and also Because stuff is easy now. Back in the day when I used Bootstrap,it was primarily for the grid system that Bootstrap offered. This was when flexbox and css grid weren't a thing and the only way of creating good looking and responsive layouts was to use floats and percentages. This seemed way too much to do on your own when all you wanted was a simple responsive website.

Flexbox changed it though, and even more did css grid. Now in 2019 both modules are well supported in all major browsers and have really simplified the process of creating responsive layouts.

Now many may argue that Bootstrap provides way more than just a flexbox based grid system like various components and utility classes.
I agree to that but when I am creating a website , I would rather prefer to create the styling and components on my own than using a framework.

This may sound ridiculous, but this is a really practical way of learning html,css and javascript and once you have done this a few times, you kind of create a front end library of your own. So the next time you have to create a component like a navbar for a new project, you simply use your library.

There are few advantages to this, first you learn a lot and real,you improve your front-end skills. Second,you know exactly how everything works(stuff like which class does what) and third , there's no unrequired code, you only use those classes that you need to.

In the end, it's all about personal preference.I personally like to create styling from scratch as I feel it gives me some additional flexibility. Bootstrap does simplify styling a lot when creating prototypes but for a portfolio website for a client? I would rather go with a tailor-made website.

Yes I'm using it.
Why? Because that's the only framework I know.

But I'm not using the entirety of it. Like many create a whole responsive website using nothing but Bootstrap, but I'm only using some of its classes, such as ones of display,margin,padding,background/text colors,width etc. So mostly the basics.

Although it's far from perfect, some classes should have much more variants, like w class has only 4: w-25|50|75|100.

For cases like this, I've created my own classes, like w-1|2|3..., or some break-point specific classes, like w-lg-1|2|3...

Also I created classes for positioning too, such as top-1|2|3.../top-md-1|2|3..., and so on.

No, I don't use Bootstrap. Why? Because I like to build my own stuff and my own design. I'm also not the biggest fan of making everything similar. There should be a design different in different projects. The only thing I use is a self-made boilerplate for a grid system (responsive design)

I do.
Professionally speaking, because I can build fast forms with it. But personally I prefer using CSS Grid and Vanilla CSS (or Sass) instead of Bootstrap.

I started my web dev career using Bootstrap and in the last year when I learned a lot of CSS that make me analyse when I have to user Bootstrap and when not.

Our current project has gone BootStrap free. We are using the HTML 5 Grid exclusively for entire site. So far the progress has been boiled down into easily repeatable css markup like this:

.grid{
  display:grid;
  grid-template-columns:repeat(auto-fit, minmax(10em, 1fr));
  grid-template-rows:repeat(auto-fit, minmax(1em, 1fr));
  grid-column-gap: 1em;
}

Tips: use repeat whenever you can with auto-fit and minmax.
The first value in minmax dictates column widths or row heights.
Use right and left margins to anchor controls so they grow/shrink based on grid only.

We also found that just about every one of our components has it's own grid layout.
This means a single page could have as many as 5-10 grids. We have not seen any performance degradation.

It took us about 2 weeks to really understand the grid...

I used to use Bootstrap, but the size and its dependency on jQuery made it feel increasingly clunky. Switched to Buefy, which has a cleaner API, results in smaller bundles, and implements Material Design.

I’m using it for a portfolio project that basically has 50 similar pages and only the info and pictures really changed. It really fights you sometimes.

If I had to redo this project I don’t know if I’d use it, but there is a lot I would change.

I make business oriented, private apps and use bootstrap and themes on top of bootstrap a lot. While designers might not like the cookie-cutter, sameness of the templates, it's a God send for business software where less design and more practicality is necessary...

No, I don't.
I feel like I still need to know more CSS before using frameworks

For my earlier projects I was using Bootstrap almost everywhere but since I found out about css-in-js, MaterialUI ans StyledComponents, Bootstrap seems not compatible with the technology I like to use. Theming is only possible with SASS, it has this clunky jQuery dependency and also adding styles to bootstrap classes with StyledComponents was absolue css hell.