What are micro frontends?

Micro frontends let teams independently develop and deploy applications composed into one product. Frameworks provide loading, lifecycles, routing and communication; runtime isolation reduces accidental interference without automatically establishing a malicious-code boundary.

Implementation comparison

Defaults vary by version and options; measure performance, compatibility and integration cost in the target project rather than using star ratings.

Solution	JS integration	Style isolation	Important limits
qiankun	single-spa lifecycles and JS sandbox	Optional scoped prefixes or ShadowDOM	Mainly limits accidental pollution
micro-app	Custom elements and JS sandbox; iframe mode depends on version	Scoped prefixes by default, optional ShadowDOM	CustomElement does not imply default ShadowDOM
Wujie	Same-origin iframe JS, document proxied to host WebComponent	ShadowDOM; evaluate fallbacks separately	Sub-apps can access window.parent
EMP / Module Federation	Build-time exposure, runtime loading/shared dependencies	Application-defined	Shared context, not browser-level isolation
iframe	Independent browsing context	Separate document	Security depends on separate origins and sandbox policy

Selection criteria

• Validate route ownership, dependencies, loading failures and rollback for independent releases.
• Test actual legacy artifacts rather than assuming every stack integrates unchanged.
• Design separate-origin iframes, sandbox policies, communication permissions and server authorization for untrusted apps; Proxy or same-origin iframes are insufficient.
• Verify first-screen performance, switching and SSR against versions and actual devices.

Routing

The host owns entry and loading rules; child-route independence and URL synchronization depend on mode and configuration. Test refreshes, back navigation, deep links and unmounting.

Solution	Routing
qiankun	activeRule activation; avoid host/child conflicts
micro-app	Virtual routes and synchronization configured by version
Wujie	Configurable synchronization of iframe history and host URL
Module Federation	Host/remote integration defines routing
iframe	Separate URL with explicit host-state communication

Web Components

CustomElement provides custom tags and lifecycles; ShadowDOM provides DOM encapsulation and style scoping. Custom elements need not create a ShadowRoot, and ShadowDOM is not an authorization or malicious-script boundary.

Style isolation

• Scoped prefixes rewrite selectors; verify global selectors, popups and dynamic styles.
• ShadowDOM isolates most selectors; handle inheritance, CSS variables and external popups.
• CSS Modules / BEM reduce naming collisions, not malicious-code risks.
• Iframes separate document styles; security still depends on origins, sandbox and communication permissions.

Communication

Solution	Common communication
qiankun	props and initGlobalState
micro-app	data, dispatch and framework APIs
Wujie	props, window.parent and bus
Module Federation	Exported functions, components or shared modules
iframe	postMessage with origin, source and payload validation

Define protocol versions, ownership, subscription cleanup and errors; frontend identity does not replace server authorization.

Implementation references

qiankun

Uses single-spa lifecycles, JS sandboxing and configurable style isolation. Verify ESM, Vite and sandbox support by version.Official documentation.

micro-app

Custom elements load sub-apps; default prefixes and optional ShadowDOM are separate modes. Verify iframe and route APIs by version; ShadowDOM does not explain JS execution or routing.Style isolation.

EMP / Module Federation

Declare exposed/shared modules at build time and load remote code with dependency negotiation at runtime, not only at build time. Design singleton settings, version constraints and failure handling.Module Federation.

Wujie

JS runs in a same-origin iframe, document is proxied to a host WebComponent and ShadowDOM isolates styles. Sub-apps can access window.parent; reduced pollution does not establish safe execution of malicious code.Implementation.