Seamless Auth

Spec sheet

Product

Seamless Auth is open-source passwordless authentication infrastructure that can be self-hosted or used as a managed service.Read 9 Oct 2026 · seamlessauth.com

Integrations

The maker documents React, Express, Fastify, and Next.js integrations, with a framework-agnostic core for other runtimes.Read 9 Oct 2026 · docs.seamlessauth.com

Audit logs

Business includes authentication audit logs and seven-day log retention; MVP includes authentication events and one-day log retention.Read 9 Oct 2026 · seamlessauth.com

Authentication methods

The product supports passkeys, magic links, email and phone OTP, and TOTP MFA.Read 9 Oct 2026 · seamlessauth.com

Framework support

The authentication core is framework agnostic and uses adapters to integrate with server frameworks.Read 9 Oct 2026 · seamlessauth.com

Frontend integration

The React SDK exposes authenticated session state without redirects, hosted login pages, or client-side token handling.Read 9 Oct 2026 · seamlessauth.com

Managed isolation

Each managed instance runs its auth service and its own database in dedicated, isolated containers on a shared network backbone.Read 9 Oct 2026 · seamlessauth.com

Notable limitation

TOTP routes exist in the auth API, but the maker says they are not yet wrapped by the React SDK or mounted by the Express adapter.Read 9 Oct 2026 · docs.seamlessauth.com

OAuth

The auth API supports OAuth provider discovery, authorization start, callback validation, and account linking.Read 9 Oct 2026 · docs.seamlessauth.com

Open source

The core is released under AGPL-3.0 and can be inspected, modified, and self-hosted at no cost.Read 9 Oct 2026 · seamlessauth.com

Security boundary

The maker says sessions are validated in the customer’s application against a signed token, so normal authenticated traffic does not round-trip to Seamless Auth.Read 9 Oct 2026 · seamlessauth.com

Self-hosting setup

The maker’s homepage says one CLI command scaffolds a web app, API, auth server, and database wired together for local operation.Read 9 Oct 2026 · seamlessauth.com

Trial terms

The trial is a full managed auth instance, requires no credit card, is limited to one per account, and is removed at the end unless upgraded.Read 9 Oct 2026 · seamlessauth.com

Who it is for

The managed MVP plan is described for early products and prototypes, while Business covers the majority of production application use cases.Read 9 Oct 2026 · seamlessauth.com

Plans and prices

Every Seamless Auth plan and price →

Where Specifiction places it

• Passwordless Authentication Software#15 of 277.9