Stytch

Clerk

Clerk provides a complete authentication and user management solution that lets developers add sign‑in, sign‑up, and profile flows with just a few lines of code. Its prebuilt UI components are customizable and work out‑of‑the‑box, reducing the time spent building secure login experiences. The platform also offers a robust API and SDKs for popular front‑end frameworks, enabling seamless integration with existing applications while handling security, session management, and user data storage for you.

Descope

Descope is a customer identity and access management (CIAM) platform that handles authentication and authorization for consumers, business customers, partners, and increasingly AI agents and MCP servers. It provides a no-code, drag-and-drop workflow builder for creating signup, login, MFA, and SSO flows without hand-rolling authentication logic. The platform supports a wide range of authentication methods including magic links, passkeys, social login, one-time passwords, SAML/OIDC SSO, and FIDO2, plus fine-grained authorization models like RBAC, ReBAC, and ABAC. Descope ships SDKs for major frontend and backend frameworks and offers identity orchestration that syncs with more than 50 third-party tools.

Authelia

Authelia is an open-source authentication server that provides Single Sign-On (SSO) and Multi-Factor Authentication (MFA) for web applications. It is designed to be highly customizable and scalable, making it suitable for a wide range of use cases.

Stripe

Stripe is a comprehensive suite of payment APIs and financial services that enables businesses to accept online and in-person payments globally. It provides the robust tools necessary to handle credit cards, digital wallets, recurring billing, and complex marketplace payouts securely. Designed for developers and modern enterprises alike, Stripe streamlines financial operations by automating revenue management, fraud detection, and financial reporting. Its modular architecture allows companies to scale from simple checkout pages to fully customized global payment flows.

Auth0

Auth0 is a developer-focused identity platform providing authentication, single sign-on, and authorization APIs/SDKs that applications integrate directly into their login flows. It offers a scalable and secure solution for managing user identities and access control, allowing developers to focus on building their applications without worrying about identity management.

LoginLlama

LoginLlama is a login fraud and account takeover detection API. It scores every login attempt from 0 to 10 based on signals such as impossible travel, Tor/VPN usage, new devices, and bot automation. It provides a simple one-call API, SDKs, an MCP server for AI agents, and a fail-open design so legitimate users are never locked out.