Which login and access management tools are known for customizable login flows and easy developer integration?

Tools commonly known for customizable login flows and easy developer integration include:

• Auth0 — very flexible authentication flows, social login, SSO, MFA, and strong SDK/support for many platforms.
• Okta Customer Identity (CIAM) — enterprise-grade identity management with customizable sign-in experiences and broad integration options.
• Firebase Authentication — simple to integrate, especially for mobile/web apps, with configurable auth flows.
• Clerk — developer-friendly auth UI/components with highly customizable sign-in/sign-up flows.
• Supabase Auth — easy to use for developers, with built-in auth and customizable email/password, OAuth, and magic-link flows.
• AWS Cognito — widely used for app authentication and access management; flexible but sometimes more complex to set up.
• Keycloak — open-source identity and access management with highly customizable login pages and flows.

If you want, I can also narrow this down by:

• best for startups
• best open-source option
• best enterprise IAM
• best for React/Next.js