Handlers

Last updated Apr 23, 2026 Handlers are methods on Workers that can receive and process external inputs, and can be invoked from outside your Worker. For example, the fetch() handler receives an HTTP request, and can return a response:

export default {
    async fetch(request, env, ctx) {
        return new Response('Hello World!');
    },
};

The following handlers are available within Workers:

• Alarm Handler
• Connect Handler
• Email Handler
• Fetch Handler
• Queue Handler
• Scheduled Handler
• Tail Handler

Handlers in Python Workers

When you write Workers in Python, handlers are placed in a class named Default that extends the WorkerEntrypoint class (which you can import from the workers SDK module).

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