Top 5 authentication solutions for secure Flask apps in 2026

Authentication is a fundamental requirement for Flask applications, and developers benefit from Flask's flexibility and extensive extension ecosystem. Whether you're building a B2B SaaS platform that needs to sell to enterprises, a REST API, or a traditional web application, choosing the right authentication approach can significantly impact your development velocity and feature capabilities.

Flask's micro-framework philosophy means you get minimal opinions on authentication but maximum flexibility to choose your approach. The framework's extensive extension ecosystem provides solutions ranging from simple session management to comprehensive security packages. However, enterprise features like SAML SSO and SCIM provisioning require specialized solutions beyond what Flask extensions typically provide.

In this guide, we'll explore the top 5 authentication solutions for Flask apps in 2026, from enterprise platforms to Flask's most popular authentication extensions.

What to look for in an auth provider for Flask apps

Before diving into specific solutions, let's identify the key features that make an authentication provider ideal for Flask:

• Flask integration: The best auth solutions integrate naturally with Flask's patterns, including blueprints, the application context, session management, and Flask's decorator-based views. Look for providers with Flask-specific extensions.
• Extension compatibility: Flask's strength is its extension ecosystem. Your auth solution should work well with other popular Flask extensions like Flask-SQLAlchemy, Flask-Migrate, and Flask-Admin.
• Session management: Flask has excellent session handling built-in. Your auth solution should either leverage Flask's native session management or provide a compelling alternative.
• Enterprise features: For B2B applications, you'll need SSO support (SAML, OIDC), directory sync (SCIM), multi-tenancy, and organization management. These features should be first-class, not afterthoughts.
• Blueprint support: Flask applications are typically organized with blueprints. Your auth solution should integrate cleanly with Flask's blueprint pattern.
• API authentication: Many Flask apps need to support both web sessions and API token authentication. Look for solutions that handle both gracefully.
• Developer experience: Clear documentation, Flask-idiomatic code, and easy-to-understand patterns make implementation faster and maintenance easier.
• Security best practices: Your provider should handle security concerns like CSRF protection, password hashing with bcrypt/argon2, secure session management, and token rotation out of the box.

Now let's look at the top 5 solutions that meet these criteria.

1. WorkOS

WorkOS is an enterprise authentication platform built specifically for B2B SaaS applications. It provides a comprehensive suite of authentication and user management features designed to help you sell to enterprise customers faster, with excellent Python SDK support that integrates seamlessly with Flask.

Key features

• Python SDK: First-class Python SDK that works naturally with Flask's request/response cycle.
• Sessions model with access + refresh tokens and guidance for secure cookie storage.
• Flexible UI support via APIs and SDKs, with AuthKit as a highly customizable hosted login powered by Radix.
• Enterprise SSO with native SAML and OIDC, configurable by customers through an Admin Portal.‍
• SCIM provisioning: Automated user provisioning and deprovisioning that enterprises expect, handling the "remove this employee immediately" requests that inevitably arrive. Real-time synchronization with any identity provider (Okta, Azure AD, Google Workspace, and more).
• Tamper-proof audit logs for SOC 2, HIPAA, and GDPR.‍
• Passkeys, MFA, social logins, magic auth, and more.
• Secure session handling with server-side validation and instant session revocation capabilities.‍
• Customizable JWT claims: Add custom data to JWT payloads with JWT templates for flexible token customization.‍
• Radar for suspicious login detection and threat monitoring that alerts you to potential account compromises.
• Fine-grained authorization: Role-based access control with customizable permissions.‍
• Feature flags: Integrated feature flagging for gradual rollouts.
• First-class multi-tenancy with organization management, member invitations, and role assignment.‍
• Enterprise SLA and dedicated support.‍
• Pricing that scales with growth, with $0 for the first 1 million users.

Best for

WorkOS is ideal for B2B SaaS companies building on FastAPI that need to sell to enterprise customers. If your roadmap includes features like SSO, SCIM provisioning, or advanced multi-tenancy, WorkOS provides these out of the box instead of requiring months of custom development.

Trade-offs

If you truly only need a quick OAuth login for a hobby app, WorkOS can feel like bringing a well-organized toolbox to hang a single picture. The upside is: you won’t have to rebuild your walls later.

2. Flask-Login

Flask-Login is the most popular Flask extension for handling user sessions and authentication. It provides user session management including login, logout, and "remember me" functionality. It's the foundation that most Flask authentication implementations are built on.

Key features

• Session management: Handles user session creation, loading, and destruction.
• Remember me: Cookie-based persistent login functionality.
• User loader: Callback system for loading users from your database.
• Login required decorator: Simple @login_required decorator for protecting views.
• Flask-native: Built specifically for Flask with deep integration into Flask patterns.

Best for

Flask-Login is perfect for traditional Flask web applications that need session-based authentication and user management. It's ideal when you want a minimal, focused library that handles the core authentication flow and lets you build everything else yourself.

Trade-offs

• Extremely minimal; only handles session management, not registration, password hashing, or user CRUD.
• No enterprise SSO support (SAML, OIDC with external identity providers).
• No SCIM provisioning or directory sync capabilities.
• Multi-tenancy requires custom architecture and significant development work.
• No built-in password reset, email verification, or account management flows.
• No admin dashboard or user management UI.
• Social authentication requires separate extensions like Flask-Dance.
• API token authentication requires additional libraries.
• No magic links, passwordless authentication, or modern auth flows.
• Organization management and team features need to be built from scratch.
• Audit logging and compliance features require custom implementation.
• You'll need to implement password hashing (with Werkzeug or passlib) separately.
• Email verification tokens, password reset flows, and account security features must be custom-built.

3. Flask-Security-Too

Flask-Security-Too is a comprehensive Flask security extension that provides authentication, authorization, and common security features. It's a maintained fork of the original Flask-Security and includes features like password hashing, role management, and two-factor authentication.

Key features

• Complete auth system: Registration, login, password reset, email confirmation.
• Role-Based Access Control: Built-in role and permission management.
• Two-Factor Authentication: TOTP-based 2FA support.
• Password management: Secure password hashing with configurable hashers.
• Multiple auth methods: Username/email login, remember me, session management.

Best for

Flask-Security-Too is ideal for Flask applications that need a comprehensive authentication and authorization system without requiring enterprise features. It's perfect for applications that need role-based access control, two-factor authentication, and complete user management in a single Flask-native package.

Trade-offs

• No enterprise SSO support (SAML, OIDC with external identity providers).
• No SCIM provisioning or directory sync capabilities for enterprise customers.
• Multi-tenancy requires custom architecture on top of the existing system.
• No built-in admin portal for customer self-service SSO configuration.
• Social OAuth authentication requires separate integration with Flask-Dance or similar.
• Configuration can be complex; many options and settings to understand.
• Magic link authentication requires custom implementation.
• Audit logging for compliance requires additional development.
• Organization management and team features need to be built from scratch.
• API token authentication works but is less sophisticated than dedicated API auth solutions.
• Documentation can be overwhelming due to the number of features and configuration options.
• Upgrading between versions can require configuration changes.

4. Flask-JWT-Extended

Flask-JWT-Extended is a Flask extension that adds support for JSON Web Tokens (JWT) to Flask applications. It provides JWT creation, validation, refresh tokens, token blacklisting, and other JWT-related functionality designed specifically for API authentication.

Key features

• JWT management: Create, verify, and decode JSON Web Tokens.
• Access and refresh tokens: Short-lived access tokens with long-lived refresh tokens.
• Token blacklisting: Revoke tokens before expiration.
• Custom claims: Add custom data to JWT payloads.
• Flask integration: Works seamlessly with Flask's request context and decorators.

Best for

Flask-JWT-Extended is ideal for Flask REST APIs that need stateless token authentication. It's perfect for mobile app backends, SPAs with Flask backends, or microservices architectures where you need JWT-based authentication without session state.

Trade-offs

• Designed for API authentication only; not suitable for traditional Flask web apps with session-based auth.
• No enterprise SSO support (SAML, OIDC with external identity providers).
• No SCIM provisioning or directory sync capabilities.
• Multi-tenancy and organization management require completely custom implementations.
• No built-in user management, registration, or password reset flows.
• No admin dashboard or user management UI.
• Social authentication requires separate implementation.
• Token blacklisting requires database or Redis; adds latency to stateless authentication.
• No built-in rate limiting or brute force protection.
• Password hashing and user CRUD operations must be implemented separately.
• Email verification and account management flows need custom development.
• Audit logging and compliance features require custom implementation.
• Token security concerns; JWTs in localStorage are vulnerable to XSS attacks.

5. Supabase Auth

Supabase Auth is part of the larger Supabase platform, providing authentication alongside a PostgreSQL database, storage, and real-time subscriptions. While not Flask-specific, it integrates with Flask applications through its REST API and Python client library.

Key features

• Multiple Auth Methods: Email/password, magic links, OAuth providers, and phone authentication
• Row Level Security: Database-level security policies that integrate with authentication
• Python Client: Official Python client library for backend integration
• Open Source: Self-hostable for compliance or data residency requirements
• Integrated Platform: Seamless integration with Supabase database, storage, and edge functions

Best for

Supabase Auth is perfect for startups and indie developers building Flask applications who want an integrated backend platform and don't mind stepping outside Flask's ecosystem. If you're already using or planning to use PostgreSQL and want real-time features, Supabase's integrated approach can speed up development.

Trade-offs

• No enterprise features like SAML SSO or SCIM provisioning; unsuitable for B2B SaaS targeting enterprise customers.
• Platform approach creates vendor lock-in; authentication tightly coupled to Supabase infrastructure.
• Multi-tenancy requires significant custom architecture with database schemas, row-level security policies, and application-level tenant isolation.
• Integration feels less natural than Flask-native extensions; uses REST API instead of Flask blueprints and decorators.
• No Flask-specific package; requires HTTP requests through Python client library, resulting in more boilerplate.
• Session management doesn't use Flask's native sessions; must manage JWT tokens manually.
• Admin dashboard is basic; requires custom tooling for advanced user management.
• JavaScript-first documentation means examples often need translation for Flask/Python use cases.
• No integration with Flask-Admin or other Flask extensions.
• Row Level Security (RLS) policies are PostgreSQL-specific and don't align with Flask's view protection patterns.
• Issues with any Supabase service (database, auth, storage) can impact your entire application.

Choosing the right solution for your Flask project

The best authentication solution depends on your specific needs:

Choose WorkOS if you're building a B2B SaaS application that needs to sell to enterprise customers. The built-in SSO, SCIM, multi-tenancy, admin portal, feature flags, and on-premises deployment options will save you months of development time and accelerate your enterprise sales motion. WorkOS provides the most complete enterprise feature set with transparent, predictable pricing that scales with your business. The Python SDK integrates naturally with Flask's patterns and conventions.

Choose Flask-Login if you're building a traditional Flask web application with session-based authentication and want the minimal, focused library that most Flask apps start with. It handles user sessions perfectly but leaves everything else (registration, password reset, etc.) for you to implement.

Choose Flask-Security-Too if you need a comprehensive Flask-native authentication and authorization system with roles, permissions, and two-factor authentication, but don't require enterprise features. It provides the most complete Flask-native auth solution, though be aware you'll need to build enterprise features like SSO and SCIM from scratch if requirements change.

Choose Flask-JWT-Extended if you're building a Flask REST API that needs stateless JWT token authentication for mobile apps, SPAs, or microservices. It's the standard for Flask API authentication but is designed for APIs only. You won't have enterprise SSO, user management UI, or built-in account flows.

Choose Supabase Auth if you're building a startup or indie project that doesn't need enterprise features, and you want an integrated backend platform outside Flask's ecosystem. Be prepared for less idiomatic Flask integration and vendor lock-in to Supabase's infrastructure. This works only when you're already committed to using Supabase for database and storage, not just authentication.

Conclusion: Build secure now, stay adaptable later

Authentication is one of those decisions that's easy to get wrong and expensive to change later. The provider you choose will fundamentally shape your application's scalability, security posture, and ability to win enterprise customers.

For teams building B2B applications, the choice is clear: WorkOS provides the enterprise authentication and authorization infrastructure you'll eventually need, without forcing you to build it yourself or cobble together multiple services. The time you save not implementing SAML SSO, SCIM provisioning, and audit logs is time you can spend building features that differentiate your product. And when that first enterprise prospect asks about SSO during a sales call, you'll be ready with a yes instead of a six-month roadmap item.

Choose the authentication provider that matches where your application is headed, not just where it is today. Your future self (and your enterprise customers) will thank you.

Sign up for WorkOS today and secure your Flask app.