Open-source Transmit Security alternatives

SuperTokens is an open-source authentication provider positioned as an alternative to Auth0, Firebase Auth and AWS Cognito. It adds secure login and session management to your apps, with SDKs for popular languages and frameworks such as Node.js, Go, Python, React and React Native.

Its architecture has three building blocks: a frontend SDK that manages session tokens and renders login UI widgets, a backend SDK that provides the APIs for sign-up, sign-in, sign-out and session refreshing, and the SuperTokens Core, an HTTP service in Java that implements the authentication logic and database operations used by the backend SDK. The feature list spans passwordless and social sign-in, email and phone with password, session handling, MFA, multi-tenant organizations with enterprise SSO, user roles, authentication between microservices, and a dashboard for managing users.

You can self-host the core to keep user data in your own database, or use the vendor's managed offering. The repository's license is listed as 'Other' on GitHub, because enterprise features sit under a separate license, so check which features you need. It suits teams that want to own authentication without building it from scratch.

ZITADEL is an identity and access management platform, open source, for teams that need more than basic login. It targets SaaS products, B2B platforms and self-hosted IAM stacks, and bundles single sign-on, multi-factor authentication, passkeys, OIDC, SAML and SCIM in an API-first design, with an emphasis on a mature multi-tenancy model.

A comparison table in the README sets it against FusionAuth, Keycloak and Auth0 or Okta on points such as open-source status, self-hosting, infrastructure-level tenants, native B2B organizations and a comprehensive event-stream audit trail. Topics list standards and features including OAuth 2, OpenID Connect, FIDO2, 2FA and passkeys. The positioning is that you can own the identity layer without vendor lock-in while still getting a polished product.

ZITADEL is written in Go and licensed under AGPL-3.0, with a website, chat, docs and blog. You can run it yourself or use the vendor's managed cloud. It suits developers and security teams building multi-tenant applications who want a self-hostable alternative to commercial identity providers.

Logto is an open-source identity platform that handles sign-in, sign-up and access control so product teams do not have to build them from scratch. It is built on OpenID Connect and OAuth 2.1, with SAML also supported, and is aimed at SaaS products and AI or agent-based platforms that need production-ready authentication.

Out of the box it provides multi-tenancy and organizations with member invites and role-based access, enterprise SSO, and prebuilt sign-in flows with a customizable interface. Sign-in options include social login, passwordless methods, MFA and Google One Tap, and it can connect to external identity providers such as Google, Azure AD and Okta. SDKs cover more than 30 frameworks, among them React, Next.js, Angular, Vue, Flutter, Go and Python.

The core is licensed under MPL-2.0 and can be self-hosted by following the OSS installation guide or run locally for development. Logto Cloud offers the same product as a fully managed service. The project also advertises support for the Model Context Protocol and agent-style AI architectures.

Hanko is an authentication and user management solution released as open source, framework-agnostic and designed around privacy-first principles such as data minimalism and phishing resistance. It is presented as an alternative to Auth0, Clerk, WorkOS and Stytch, written in Go, with an API-first and lightweight design.

It supports modern sign-in methods including passwords, email passcodes, passkeys, MFA with TOTP and security keys, social logins such as Apple, Google and GitHub, custom OIDC and OAuth connections and SAML enterprise SSO. Configuration is flexible, for example passkey-only or OAuth-only setups, and passwords can be deletable by users. Hanko Elements web components make integration quick, a JS SDK is available, webhooks and server-side sessions with remote revocation are included, and a full API supports custom front ends. Organizations, roles and permissions plus mobile SDKs are on the roadmap.

You can self-host Hanko or use it as a fully managed service on Hanko Cloud. The repository lists the licence as Other, so review the licence file for the terms. It suits developers who want to own their authentication stack without building it from scratch.

Authgear is an open-source authentication solution for consumer-facing applications, presented as an alternative to Auth0, Keycloak, Clerk, and Firebase Auth. It is written in Go and released under the Apache-2.0 license, and can be self-hosted or used on Authgear Cloud. SDKs and a management portal help developers get started in a few minutes.

Out-of-the-box features include passwordless login through magic link or one-time codes over email, SMS, and WhatsApp, passkeys, pre-built sign-up, login, and account settings pages, biometric login on iOS and Android, and two-factor authentication with TOTP, SMS, or email. It supports OIDC, OAuth 2.0, and SAML for SSO, enterprise connections such as ADFS and LDAP, and security features like audit logs, brute-force protection, and rate limits.

The Authgear Portal provides a web interface for user management and configuration, and an Admin API in GraphQL manages resources programmatically. It suits SaaS products and multi-app ecosystems that need flexible authentication without building it themselves.