Inngest Middleware

Inngest Middleware

Master Inngest middleware to handle cross-cutting concerns like logging, error tracking, dependency injection, and data transformation. Middleware runs at key points in the function lifecycle, enabling powerful patterns for observability and shared functionality.

These skills are focused on TypeScript. For Python or Go, refer to the Inngest documentation for language-specific guidance. Core concepts apply across all languages.

Note: The middleware system was significantly rewritten in v4. The lifecycle hooks documented here reflect the v4 API. If migrating from v3, consult the migration guide for details on breaking changes.

⚠ For Realtime use the inngest-realtime skill, NOT this one. Inngest v3 used realtimeMiddleware() from @inngest/realtime to inject a publish arg into function handlers. v4 ships realtime natively — step.realtime.publish is built-in, no middleware required. Do NOT install @inngest/realtime on a v4 project (it's a v3-era package and produces TypeError: Cls is not a constructor at runtime). See the inngest-realtime skill for the v4 pattern.

What is Middleware?

Middleware allows code to run at various points in an Inngest client's lifecycle - during function execution, event sending, and more. Think of middleware as hooks into the Inngest execution pipeline.

When to use middleware:

• Observability: Add logging, tracing, or metrics
• Dependency injection: Share client instances across functions
• Data transformation: Encrypt/decrypt, validate, or enrich data
• Error handling: Custom error tracking and alerting
• Authentication: Validate user context or permissions

Middleware Lifecycle

Middleware can be registered at client-level (affects all functions) or function-level (affects specific functions).

Execution Order

const inngest = new Inngest({
  id: "my-app",
  middleware: [
    loggingMiddleware, // Runs 1st
    errorMiddleware, // Runs 2nd
  ],
});

inngest.createFunction(
  {
    id: "example",