when you say you’re “currently a software developer that works for startups” does this mean you have one employer that you work for, they give you a paycheck every couple of weeks along with healthcare, 401(k), equity, etc? or does this mean that you find a company that needs help, do some coding for them and they pay you for that help, then you move on to the next company?
if it’s the former, go to your employer and ask them if you can start working remotely as a “trial” - say for a few weeks. bust ass and make sure you’re delivering what they want and more. answer e-mails and phone calls / texts in a timely manner so they can see that just because you’re not behind the desk doesn’t mean you’re not working. after the trial is over, discuss and show them it worked out well and ask to work remotely full-time. that’s essentially what i did for nearly 10 years.
if you’re asking “how do i find clients”, that’s another story all together.
there are plenty of resources available but it comes down to either working for yourself - as a consultant / coder-for-hire or monetizing your own projects.