Auth.js vs Stack Auth: Features, Pricing and User Reviews 2026

Auth.js is completely free to use with no pricing tiers or hidden costs. As an open-source project, it is licensed under the ISC license, which allows anyone to use, modify, and distribute the software freely for both personal and commercial projects.

There are no subscription fees, no usage limits, and no charges for any features. All capabilities, including support for unlimited providers, database integrations, and advanced security features, are available at no cost. This makes Auth.js an excellent choice for projects of any size, from small personal websites to large enterprise applications.

The project is maintained by a community of contributors and is now part of Better Auth Inc. Developers can contribute to the project, report issues, and access community support through GitHub discussions completely free of charge.

Stack Auth offers transparent pricing that scales with your needs. The Free plan is perfect for individuals and small projects, supporting up to 10,000 users with unlimited projects and teams. You get one dashboard administrator and access to all core authentication features.

The Team plan costs $49 per month and increases your user limit to 50,000 users. It includes three dashboard administrators, with additional admins available at $49 each. This plan is ideal for early startups and small teams building their products.

The Growth plan at $299 per month removes all user limits entirely. You get unlimited users, projects, and teams, along with five dashboard administrators included. Additional admins cost $49 each. This plan is designed for growing businesses that need to scale without worrying about user count restrictions.

All plans include the same core features, with the main differences being user limits and admin accounts.