[Growth Hacking] How would you promote a B2B Saas product to developers?

Growth hacking is what comes to mind. I would usually search for LinkedIn profiles then cold message them saying "hey, try our API for free and let me know what you think. I think you'll find it of great value."

I think the question to ask is where do developers spend their time, no? Google? Reddit? Stack Overflow?

Instead of paying for advertising (which can be very expensive for B2B products), I'd like to connect with them directly.

Thoughts?