FusionAuth is the authentication and authorization platform engineered for developers who demand flexibility and control. Built from the ground up to integrate with any stack, every feature — from user registration to MFA and SSO — is exposed via a modern, well-documented API.
Support for every major identity protocol is included out of the box: OIDC, SAML, OAuth2, JWT, passwordless login, social sign-on, and more. Whether you’re building a greenfield app or retrofitting auth into a legacy system, FusionAuth adapts to your use case — not the other way around.
Need compliance? FusionAuth helps you meet GDPR, HIPAA, and COPPA standards quickly and reliably.
Deploy it your way: install on Linux, Windows, macOS, Docker, or Kubernetes — or go with FusionAuth Cloud, our managed SaaS hosting. No black boxes. No vendor lock-in. Just powerful, customizable auth that works the way you do.
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Auth0 takes a modern approach to Identity and enables organizations to provide secure access to any application, for any user. Auth0 is highly customizable, and simple yet flexible. Safeguarding billions of login transactions each month, Auth0 delivers convenience, privacy, and security so customers can focus on innovation.
With Auth0, you can rapidly integrate authentication and authorization for web, mobile, and legacy applications, with new Fine Grained Authorization (FGA) that goes beyond role-based access control.
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UploadThing
UploadThing is a versatile, open-source solution for file uploads tailored specifically for full-stack applications using TypeScript. It streamlines the integration of file uploads by enabling developers to set up File Routes that define permitted file types, size limits, and the number of uploads allowed. The platform offers SDKs compatible with a range of frameworks, such as Next.js, Astro, SolidStart, SvelteKit, and Nuxt, along with backend support for Express, Fastify, H3, and more. Client-side file uploads are made easy through the use of components and hooks, allowing for smooth integration with popular frontend libraries like React and Vue. With a focus on both security and ease of use, UploadThing manages authentication on the developer's server while overseeing the file upload process on its own infrastructure. This method ensures that server-side authorization can be achieved without the burden of file processing on the developer's end, ultimately enhancing the overall user experience. Furthermore, this solution is ideal for developers seeking a reliable and efficient way to handle file uploads in their applications.
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Scalekit
Scalekit is an authentication and integration platform designed specifically for AI agents that need to securely connect with SaaS applications, APIs, MCP servers, databases, and internal systems. The platform enables agents to act on behalf of individual users instead of using shared service accounts, ensuring every action follows the user's identity, permissions, and approved access scopes. Scalekit manages delegated OAuth authentication, secure credential vaulting, token lifecycle management, authorization checks, and API communication without requiring developers to build that infrastructure themselves. Developers can connect to more than 100 prebuilt integrations or create custom connectors for proprietary services and internal APIs. Built-in handling for pagination, retries, rate limiting, and error management simplifies tool execution while improving application reliability. Every request is logged with a complete delegation chain that records the user, agent, connector, permissions, and resulting actions for auditing and compliance. The platform supports encrypted credential storage, regional deployments, private cloud options, SIEM integrations, and enterprise-grade security controls. Scalekit also extends beyond AI agents by providing SaaS authentication capabilities such as SSO, SCIM provisioning, RBAC, passwordless authentication, and user management. By combining delegated identity, secure authentication, and production-ready connector infrastructure, Scalekit enables organizations to build trustworthy AI agents without the complexity of managing authentication themselves.
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