Tool Review: MicroAuthJS — Plug-and-Play Auth UI (with Enterprise Options)

Authentication UIs are a common source of friction for teams: they require careful UX for errors, security flows for multi-factor authentication, and tight integrations for SSO. MicroAuthJS presents a compact client-side UI that integrates with common identity providers and offers enterprise packages for SAML/SCIM support.

Security posture

MicroAuthJS takes a conservative approach: the client-side component handles presentation and flows but never stores credentials. Token exchange is performed via your backend using OAuth2 authorization code flows with PKCE. The default configuration encourages short-lived tokens and refresh token rotation. We audited the default settings and found sensible defaults, but enterprise setups with SAML required additional server-side adapters.

Customization

The UI is makeupable via CSS variables and small component overrides. For teams that require deep customization, MicroAuthJS exposes render hooks and slot-like injection points to override default visuals and flows. The tradeoff is that deep customizations pull in more code and may require additional tests to ensure security flows aren't broken by custom markup.

Integration experience

Integrating MicroAuthJS into an existing SPA is straightforward. The quickstart gets you from install to a working login in minutes. However, SSO and enterprise features require a slightly more involved server-side adapter and certificate exchange, which the enterprise plan helps streamline with onboarding assistance.

Pros and cons

Pros:

• Fast developer integration with good docs.
• Secure defaults using authorization code with PKCE.
• Customizable visuals via CSS variables and hooks.

Cons:

• Enterprise SAML/SCIM requires paid plan.
• Deep customizations increase integration risk.

Performance and footprint

The client bundle is small for basic use — under 12KB gzipped for the core UI. Advanced features (widgetized social logins, SAML adapters) add to the footprint but are optional. The component is friendly to code-splitting and can be lazy-loaded on login routes.

Enterprise readiness

MicroAuthJS offers SLAs and dedicated onboarding for enterprise customers. They provide a recommended server-side reference app and a set of automated integration tests to validate assertion flows. For regulated industries, the enterprise package includes additional security reviews and a compliance addendum.

Verdict

MicroAuthJS is a solid option for teams who want to ship an authentication UX fast while preserving secure flows. If you need SAML/SCIM or dedicated compliance support, the enterprise offering is sensible. For pure consumer apps, the open core is lightweight, secure and highly customizable via tokens.