Limits (28)·续

Outbound WebSocket connections also count toward this limit.

Once response headers arrive for a connection, it no longer counts toward the six-connection limit. This means a Worker can have many connections open simultaneously, as long as no more than six are in the initial "waiting for headers" phase at the same time. If a seventh connection is attempted while six are already waiting for headers, it is queued until one of the existing connections receives its response headers.

If you use fetch() but do not need the response body, calling response.body.cancel() is still good practice to free memory:

src/index.jsjs

const response = await fetch(url);

// Only read the response body for successful responses
if (response.status <= 299) {
    // Call response.json(), response.text() or otherwise process the body
} else {
    // Explicitly cancel it
    response.body.cancel();
}

src/index.tsts

const response = await fetch(url);

// Only read the response body for successful responses
if (response.status <= 299) {
    // Call response.json(), response.text() or otherwise process the body
} else {
    // Explicitly cancel it
    response.body.cancel();
}

Note

The runtime measures simultaneous open connections from the top-level request. Workers triggered via Service bindings share the same connection limit.

Environment variables

Worker size

There is no compressed size limit. Only the uncompressed bundle size counts.

Larger Worker bundles can impact startup time. To check your Worker bundle size:

wrangler deploy --outdir bundled/ --dry-run

Total Upload: 259.61 KiB / gzip: 47.23 KiB

The Total Upload value is your uncompressed bundle size. The gzip value is shown for reference but is not a limit.

To reduce Worker size:

• Remove unnecessary dependencies and packages.
• Store configuration files, static assets, and binary data in KV, R2, D1, or Workers Static Assets instead of bundling them.
• Split functionality across multiple Workers using Service bindings.

Worker startup time

A Worker must parse and execute its global scope (top-level code outside of handlers) within 1 second. Larger bundles and expensive initialization code in global scope increase startup time.

When the platform rejects a deployment because the Worker exceeds the startup time limit, the validation returns the error Script startup exceeded CPU time limit (error code 10021). Wrangler automatically generates a CPU profile that you can import into Chrome DevTools or open in VS Code. Refer to wrangler check startup for more details.

To measure startup time, run npx wrangler@latest deploy or npx wrangler@latest versions upload. Wrangler reports startup_time_ms in the output.

To reduce startup time, avoid expensive work in global scope. Move initialization logic into your handler or to build time. For example, generating or consuming a large schema at the top level is a common cause of exceeding this limit.

Need a higher limit?

To request an adjustment to a limit, complete the Limit Increase Request Form ↗︎. If the limit can be increased, Cloudflare will contact you with next steps.

Number of Workers

If you are building a platform where your end customers deploy their own sites or applications, use Workers for Platforms, which runs an unlimited number of user Workers.

Routes and domains

Routes with wrangler dev --remote

When you run a remote development session using the --remote flag, Cloudflare enforces a limit of 50 routes per zone. The Quick Editor in the Cloudflare dashboard also uses wrangler dev --remote, so the same limit applies.

If your zone has more than 50 routes, you cannot run a remote session until you remove routes to get under the limit.

If you require more than 1,000 routes or 1,000 routed zones per Worker, consider using Workers for Platforms. If you require more than 100 custom domains per zone, consider using a wildcard route.

Cache API limits

Calls per request is the number of put(), match(), or delete() Cache API calls per request. This shares the same quota as subrequests (fetch()).

Note

The size of chunked response bodies (Transfer-Encoding: chunked) is not known in advance. Calling .put() with such a response blocks subsequent .put() calls until the current one completes.

Log size

This limit covers all data emitted via console.log() statements, exceptions, request metadata, and headers for a single request. After exceeding this limit, the system does not record additional context for that request in logs, tail logs, or Tail Workers.

Refer to the Workers Trace Event Logpush documentation for limits on fields sent to Logpush destinations.

Image Resizing with Workers

Refer to the Image Resizing documentation for limits that apply when using Image Resizing with Workers.

Static Assets

Note

To use the increased file count limits in Wrangler, you must use version 4.34.0 or higher.

Unbound and Bundled plan limits

Note

Unbound and Bundled plans have been deprecated and are no longer available for new accounts.

If your Worker is on an Unbound plan, limits match the Workers Paid plan.

If your Worker is on a Bundled plan, limits match the Workers Paid plan with these exceptions:

Bundled plan Workers have no duration limits for Cron Triggers, Durable Object Alarms, or Queue Consumers.

Wall time limits by invocation type

Wall time (also called wall-clock time) is the total elapsed time from the start to end of an invocation, including time spent waiting on network requests, I/O, and other asynchronous operations. This is distinct from CPU time, which only measures time the CPU spends actively executing your code.

The following table summarizes the wall time limits for different types of Worker invocations across the developer platform:

Related resources

• KV limits
• Durable Object limits
• Queues limits
• Workers errors reference

Footnotes

1. If you need a higher Worker limit, use Workers for Platforms. ↩ ↩²

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