If you bootstrap from nothing, go from coworkers. Some of your coworkers will have some groups of doing something (skiing, hiking, music playing, etc.). Show you interest and get invited. There will be new people there.
There are also other events where you naturally meet people. I’m just throwing out some ideas, if case they are helpful.
For instance, taking group classes. My girlfriend made quite a few friends in her Muay Thai class.
Dog walking. My college friend recently adopted a dog, and has since known a lot of other dog keepers.
You can meet other computer people at conferences, too.
I myself is quite introverted, too. But being introverted doesn’t mean you are left with scraps. There are still occasions where interacting with other people is both necessary and natural. If you put yourself in those situations from time to time, you’ll find a few who fit your rhythm.
Another thing is to offer a helping hand to people. Owing each other favors is the most effective bonding agent in my experience. I have a personal rule of “always be helpful”, and I think that has earned me quite a few very earnest friendships, despite my being not very chatty at all.