WorkOS

Founded in 2019 by solo founder Michael Grinich (previously founder of Nylas) and based in San Francisco, WorkOS provides the identity and enterprise-readiness infrastructure that lets a startup sell to large organizations without rebuilding its auth stack. Its APIs cover single sign-on, SCIM directory sync, audit logging, fine-grained authorization, and AuthKit, a hosted authentication and user-management layer. The company became known as the identity backbone of the AI wave, with customers including OpenAI, Anthropic, Cursor, Perplexity, and Vercel, and in early 2026 raised a $100M Series C at a $2B valuation led by Meritech and Sapphire while operating with under 100 employees.