Stytch
Best for
API-first auth for AI startups; headless identity with flexible session management
Limitations
No FGA, no dedicated agent SDK, no human-in-the-loop; good primitives but requires more DIY for complex agent patterns
Features
Frameworks
SDK Languages
Compliance
Stytch
Stytch is popular in AI startup stacks because it's API-first, flexible, and gets out of the way. It supports a wide range of authentication methods (magic links, OTP, OAuth, biometrics, passkeys) without forcing a specific UI pattern.
For agents, the relevant capabilities are M2M tokens, session management with long-lived sessions, and impersonation support. Token delegation is achievable through standard OAuth flows.
Stytch doesn't have purpose-built agent features like FGA or human-in-the-loop approval. It's a strong base layer for developers who want control and prefer to build agent authorization logic themselves rather than rely on SDK-level abstractions.
Agent-specific features:
- M2M tokens for agent service authentication
- Flexible session management (useful for long-running agents)
- Impersonation for agent-acting-as-user scenarios
- OAuth token delegation through standard flows