When Seamless Auth fits, and when it does not
Seamless Auth does less than most identity platforms, on purpose. Each page below says when the other product is the better choice and when Seamless Auth is, summarised from the full comparison in the docs, where every claim is sourced and dated.
Auth0, owned by Okta, is a hosted identity platform with a broad feature set. Seamless Auth is an open source, passwordless-only auth server that you self-host or run on the managed service. It does much less than Auth0, on purpose.
Keycloak and Seamless Auth are both open source (Apache-2.0) and meant to be self-hosted. Keycloak is a full identity and access management server. Seamless Auth is a passwordless-only auth server for your own applications that lets your app render its own sign-in screens.
Amazon Cognito user pools are an AWS-operated identity service. Seamless Auth is an open source, passwordless-only auth server that you self-host, on AWS or anywhere else, or run on the managed service.
Firebase Authentication is a Google-operated sign-in service, with more features behind the paid Identity Platform upgrade. Seamless Auth is an open source, passwordless-only auth server that you self-host or run on the managed service.
What it costs
Prices change, so they live in the docs, each with its source and the date it was checked. The cost calculator puts Auth0 and Okta Customer Identity list prices next to the cost of running Seamless Auth yourself.
Open the cost calculator →More in the docs
The docs also compare Seamless Auth with Clerk, Better Auth and Supabase Auth.