REST API Startups

Nylas, co-founded by Christine Spang, started as an effort to build a power-user email client but pivoted to a developer API that abstracts email, calendar, and contacts integration. The company launched its API as open source on GitHub, then moved to a per-connected-mailbox SaaS model, and now reports about 200 paying customers and revenue in the millions per year.

John Yongfook is a solo founder who built Banner Bear, an image and video generation API, after leaving corporate life at Aviva insurance. Starting with $200k in savings, he launched 7 products before finding success with Banner Bear, which now generates $16k MRR by targeting both social media managers and digital agencies with automated creative tasks.