Modules

Last updated Jan 28, 2026 - Modules Reference

Enabling Modules

Miniflare supports both the traditional service-worker and the newer modules formats for writing workers. To use the modules format, enable it with:

const mf = new Miniflare({
    modules: true,
});

You can then use modules worker scripts like the following:

export default {
    async fetch(request, env, ctx) {
        // - `request` is the incoming `Request` instance
        // - `env` contains bindings, KV namespaces, Durable Objects, etc
        // - `ctx` contains `waitUntil` and `passThroughOnException` methods
        return new Response("Hello Miniflare!");
    },
    async scheduled(controller, env, ctx) {
        // - `controller` contains `scheduledTime` and `cron` properties
        // - `env` contains bindings, KV namespaces, Durable Objects, etc
        // - `ctx` contains the `waitUntil` method
        console.log("Doing something scheduled...");
    },
};

String scripts via the script option are supported using the modules format, but you cannot import other modules using them. You must use a script file via the scriptPath option for this.

Module Rules

Miniflare supports all module types: ESModule, CommonJS, Text, Data and CompiledWasm. You can specify additional module resolution rules as follows:

const mf = new Miniflare({
    modulesRules: [
        { type: "ESModule", include: ["**/*.js"], fallthrough: true },
        { type: "Text", include: ["**/*.txt"] },
    ],
});

Default Rules

The following rules are automatically added to the end of your modules rules list. You can override them by specifying rules matching the same globs:

[
    { type: "ESModule", include: ["**/*.mjs"] },
    { type: "CommonJS", include: ["**/*.js", "**/*.cjs"] },
];

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description: Miniflare allows you to run multiple workers in the same instance. All Workers can be defined at the same level, using the workers option. title: Multiple Workers image: https://developers.cloudflare.com/workers/testing/miniflare/core/multiple-workers/og.png?v=2c662819c743635d

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