Auth and identity

aws.amazon.com

AWS's managed user pools and identity service with a permanent 10,000 MAU free tier, low per-MAU prices and tight integration with other AWS services.

appwrite.io

Hosted Appwrite, an open-source backend with a database, auth, file storage, functions, messaging and site hosting, with a free plan and a $25/mo Pro plan per project.

wso2.com

WSO2's hosted identity service with separate B2C, B2B and workforce plans, a free tier of 7,500 consumer MAU and a pay-as-you-go plan from $20 a month.

auth0.com

Okta's hosted customer identity platform with 30+ SDKs, separate B2C and B2B price lists, and a free tier that now includes one enterprise SSO connection and SCIM.

authelia.com

A lightweight Apache-licensed SSO and multi-factor portal written in Go that sits beside your reverse proxy and is also an OpenID Certified OIDC provider.

goauthentik.io

A self-hosted open-source identity provider speaking OIDC, SAML, LDAP, SCIM, RADIUS and proxy auth, popular with homelabs and increasingly used by companies with an enterprise licence.

authgear.com

Open-source customer identity with no feature gating: even the free cloud plan has unlimited MAU, passkeys, SAML SSO and RBAC, and a $299 one-time self-hosted licence is offered.

better-auth.com

A free, open-source TypeScript auth framework that runs inside your own app and database, with a plugin for almost every feature and an optional paid dashboard and security service.

casdoor.org

An open-source Go identity server with a web UI that speaks OAuth 2.0, OIDC, SAML, CAS, LDAP and SCIM, supports 100+ identity providers, and adds an MCP server and agent auth.

clerk.com

Hosted authentication and user management with drop-in React-style components, B2B organizations and billing, priced on monthly retained users rather than sign-ups.

descope.com

Customer and AI-agent identity built around drag-and-drop login flows, with a free plan of 7,500 MAU and three SSO connections.

firebase.google.com

Google's app backend platform: Cloud Firestore and Realtime Database for synced NoSQL data, Firebase Authentication, hosting, functions and storage, with a no-card free plan.

frontegg.com

Low-code customer identity for B2B SaaS, with a pay-as-you-go plan that starts free for 7,500 MAU and includes five SSO or SCIM enterprise connections.

fusionauth.io

A downloadable customer identity server whose Community edition is free to self-host with unlimited users, plus paid licences and hosting for premium features and support.

hanko.io

German, open-source authentication with passkeys as a first-class method, EU hosting, 10,000 free MAU on Hanko Cloud and a $29 Pro plan.

stack-auth.com

Open-source auth and user management for SaaS, formerly Stack Auth, with teams, RBAC, payments and analytics; free to 10,000 users hosted, or self-hosted.

kanidm.com

A Rust identity management server that combines an OIDC provider, passkeys, Linux/UNIX login, SSH key distribution, RADIUS and a read-only LDAPS gateway in one self-hosted package.

keycloak.org

The long-established Apache-licensed identity and access management server: OIDC, OAuth 2.0 and SAML, LDAP/AD federation, identity brokering and fine-grained authorization, self-hosted.

kinde.com

Hosted auth bundled with subscription billing and feature flags, free to 10,500 MAU, with users on paid subscriptions billed through Kinde not counted.

logto.io

Open-source OIDC and OAuth 2.1 auth with organizations, enterprise SSO and RBAC, free to 50,000 MAU on Logto Cloud and billed by access tokens after that.

microsoft.com

Microsoft's customer and guest identity service, successor to Azure AD B2C, free for the first 50,000 monthly active users and billed through an Azure subscription.

nhost.io

Open-source backend platform that gives each project a dedicated PostgreSQL database with an instant Hasura GraphQL API, authentication, file storage and serverless functions.

thenile.dev

Serverless PostgreSQL built for B2B SaaS: each customer gets a virtual tenant database inside one Postgres, with tenant isolation, pgvector and built-in auth.

ory.com

Headless, API-first identity from the makers of the open-source Kratos, Hydra and Keto projects, offered self-hosted or as the Ory Network SaaS billed per average daily active user.

pocket-id.org

A small, self-hosted OpenID Connect Certified provider where users sign in only with passkeys, popular with self-hosters who find Keycloak too heavy.

propelauth.com

Hosted authentication built for B2B products, with organizations as a core concept, 10,000 free MAU and unlimited SAML/OIDC SSO connections from the $150 Growth plan.

scalekit.com

Auth runtime for AI agents: delegated OAuth, an encrypted token vault and 500+ connectors so agents act as the user, plus drop-in OAuth 2.1 for MCP servers.

stytch.com

API-first authentication with multi-tenant B2B organizations, five free SSO or SCIM connections, and built-in bot and fraud detection; now part of Twilio.

supabase.com

Open-source Postgres platform that bundles a dedicated database with auth, file storage, edge functions, realtime and auto-generated REST and GraphQL APIs.

supertokens.com

Open-source login and session management that runs on your own domain, free to self-host at any scale, or managed at $0.02 per monthly active user.

workos.com

Hosted user management free up to one million MAU, with enterprise SSO, SCIM directory sync and audit logs sold per connection for B2B SaaS.

zitadel.com

Open-source, multi-tenant identity platform from Switzerland, self-hosted or as Zitadel Cloud with data residency in the EU, US, Switzerland or Australia and pricing by daily active users.