Freedom251 › Passwordless Authentication Software
Seamless Auth
What Seamless Auth is
Seamless Auth provides open-source passwordless authentication infrastructure as a self-hosted or managed service. Supported methods include passkeys, magic links, email and phone OTP, OAuth, and TOTP MFA. The core uses the AGPL-3.0 license and can be inspected, modified, and self-hosted at no cost. Its framework-agnostic design uses adapters, with documented React, Express, Fastify, and Next.js integrations. The React SDK exposes session state without redirects, hosted login pages, or client-side token handling. Applications validate sessions against signed tokens, so ordinary authenticated traffic does not need to return to Seamless Auth. Managed instances run the auth service and database in dedicated, isolated containers. The managed trial is a full 14-day instance, costs 0.00 USD, needs no credit card, and is limited to one per account. MVP costs $49 a month; Business costs $149 a month. TOTP routes are not yet wrapped by the React SDK or Express adapter.
Who it suits
It suits teams building passwordless login who want self-hosting or managed infrastructure. MVP targets early products and prototypes, while Business is described for most production application needs.
What it does well
- Open-source AGPL-3.0 authentication core
- Passkeys, magic links, OTP, and OAuth
- Self-hosted or managed deployment
- Framework adapters for React and server tools
- 14-day managed trial without credit card
What to know first
- No free plan beyond the trial
- TOTP lacks React SDK and Express adapter support
- Trial limited to one per account
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Free trial | $0 for 14 days · Full managed auth instance · Passkeys, magic links, email and phone OTP, TOTP MFA · One trial per account | Free |
| Business | $149 per month · Unlimited users · Dedicated auth service and database · Authentication audit logs · Configurable rate limits and TTLs · 7 day log retention | $149 a month |
| MVP | $49 per month · Unlimited users · Dedicated auth service and database · Authentication events · 1 day log retention | $49 a month |
| Enterprise | Tailored deployments and support; contact for details · Advanced compliance requirements · Higher scale · Custom infrastructure needs | On request |
As seamlessauth.com lists them, read 9 Oct 2026. The maker's own page has the final word.
Verdict
Seamless Auth offers flexible passwordless methods, open-source self-hosting, and managed plans for different product stages. The incomplete TOTP adapter coverage is an important implementation limitation.
Facts from Seamless Auth's own pages
- Audit logs
- Business includes authentication audit logs and seven-day log retention; MVP includes authentication events and one-day log retention. · seamlessauth.com, 9 Oct 2026
- Authentication methods
- The product supports passkeys, magic links, email and phone OTP, and TOTP MFA. · seamlessauth.com, 9 Oct 2026
- Framework support
- The authentication core is framework agnostic and uses adapters to integrate with server frameworks. · seamlessauth.com, 9 Oct 2026
- Frontend integration
- The React SDK exposes authenticated session state without redirects, hosted login pages, or client-side token handling. · seamlessauth.com, 9 Oct 2026
- Integrations
- The maker documents React, Express, Fastify, and Next.js integrations, with a framework-agnostic core for other runtimes. · docs.seamlessauth.com, 9 Oct 2026
- Managed isolation
- Each managed instance runs its auth service and its own database in dedicated, isolated containers on a shared network backbone. · seamlessauth.com, 9 Oct 2026
- 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. · docs.seamlessauth.com, 9 Oct 2026
- OAuth
- The auth API supports OAuth provider discovery, authorization start, callback validation, and account linking. · docs.seamlessauth.com, 9 Oct 2026
- Open source
- The core is released under AGPL-3.0 and can be inspected, modified, and self-hosted at no cost. · seamlessauth.com, 9 Oct 2026
- Product
- Seamless Auth is open-source passwordless authentication infrastructure that can be self-hosted or used as a managed service. · seamlessauth.com, 9 Oct 2026
- 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. · seamlessauth.com, 9 Oct 2026
- 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. · seamlessauth.com, 9 Oct 2026
- 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. · seamlessauth.com, 9 Oct 2026
- 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. · seamlessauth.com, 9 Oct 2026
Where Seamless Auth stands on Freedom251
- Passwordless Authentication Software#22 of 27