My friend launched EnvKey (https://www.envkey.com/ https://www.envkey.com/) completely solo and grew it slowly over time. He eventually went through YC and too

My friend launched EnvKey (https://www.envkey.com/ https://www.envkey.com/) completely solo and grew it slowly over time. He eventually went through YC and took on investment but the first few years were bootstrapped. But he's still solo with a few freelancers.