BambooHR (Onboarding-Only via API)

BambooHR offers its onboarding functionality as a standalone, API-first product for companies that want to embed a best-in-class onboarding experience directly into their own applications or portals. It provides all the core features-checklists, e-signatures, tasks-via API.

This is a paid developer product. It scores for its unique approach, catering to tech companies and platforms that require a seamless, branded onboarding flow deeply integrated into their existing product ecosystem, rather than a separate HRIS.