I'm self taught and went through Triplebyte. They make you take a small quiz and technical screen anonymously, and then they pair you up with around 8 startups (mostly YC).

Here's my referral link, should you want to use it (we each get $1500): https://triplebyte.com/iv/YY8SRsU/cp.

If you need any help, my email is `<my username>cs@gmail.com`.