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Changelog

New updates and improvements at Cloudflare.

Workers Analytics Engine SQL now supports filtering using HAVING and LIKE

You can now use the HAVING clause and LIKE pattern matching operators in Workers Analytics Engine ↗︎.

Workers Analytics Engine allows you to ingest and store high-cardinality data at scale and query your data through a simple SQL API.

Filtering using HAVING

The HAVING clause complements the WHERE clause by enabling you to filter groups based on aggregate values. While WHERE filters rows before aggregation, HAVING filters groups after aggregation is complete.

You can use HAVING to filter groups where the average exceeds a threshold:

SELECT
    blob1 AS probe_name,
    avg(double1) AS average_temp
FROM temperature_readings
GROUP BY probe_name
HAVING average_temp > 10

You can also filter groups based on aggregates such as the number of items in the group:

SELECT
    blob1 AS probe_name,
    count() AS num_readings
FROM temperature_readings
GROUP BY probe_name
HAVING num_readings > 100

Pattern matching using LIKE

The new pattern matching operators enable you to search for strings that match specific patterns using wildcard characters:

  • LIKE - case-sensitive pattern matching
  • NOT LIKE - case-sensitive pattern exclusion
  • ILIKE - case-insensitive pattern matching
  • NOT ILIKE - case-insensitive pattern exclusion

Pattern matching supports two wildcard characters: % (matches zero or more characters) and _ (matches exactly one character).

You can match strings starting with a prefix:

SELECT *
FROM logs
WHERE blob1 LIKE 'error%'

You can also match file extensions (case-insensitive):

SELECT *
FROM requests
WHERE blob2 ILIKE '%.jpg'

Another example is excluding strings containing specific text:

SELECT *
FROM events
WHERE blob3 NOT ILIKE '%debug%'

Ready to get started?

Learn more about the HAVING clause or pattern matching operators in the Workers Analytics Engine SQL reference documentation.

Build microfrontend applications on Workers

You can now deploy microfrontends to Cloudflare, splitting a single application into smaller, independently deployable units that render as one cohesive application. This lets different teams using different frameworks develop, test, and deploy each microfrontend without coordinating releases.

Microfrontends solve several challenges for large-scale applications:

  • Independent deployments: Teams deploy updates on their own schedule without redeploying the entire application
  • Framework flexibility: Build multi-framework applications (for example, Astro, Remix, and Next.js in one app)
  • Gradual migration: Migrate from a monolith to a distributed architecture incrementally

Create a microfrontend project:

Deploy to Cloudflare

This template automatically creates a router worker with pre-configured routing logic, and lets you configure Service bindings to Workers you have already deployed to your Cloudflare account. The router Worker analyzes incoming requests, matches them against configured routes, and forwards requests to the appropriate microfrontend via service bindings. The router automatically rewrites HTML, CSS, and headers to ensure assets load correctly from each microfrontend's mount path. The router includes advanced features like preloading for faster navigation between microfrontends, smooth page transitions using the View Transitions API, and automatic path rewriting for assets, redirects, and cookies.

Each microfrontend can be a full-framework application, a static site with Workers Static Assets, or any other Worker-based application.

Get started with the microfrontends template ↗︎, or read the microfrontends documentation for implementation details.

Static prerendering support for TanStack Start

TanStack Start ↗︎ apps can now prerender routes to static HTML at build time with access to build time environment variables and bindings, and serve them as static assets. To enable prerendering, configure the prerender option of the TanStack Start plugin in your Vite config:

vite.config.tsts
import { defineConfig } from "vite";
import { cloudflare } from "@cloudflare/vite-plugin";
import { tanstackStart } from "@tanstack/react-start/plugin/vite";

export default defineConfig({
  plugins: [
    cloudflare({ viteEnvironment: { name: "ssr" } }),
    tanstackStart({
      prerender: {
        enabled: true,
      },
    }),
  ],
});

This feature requires @tanstack/react-start v1.138.0 or later. See the TanStack Start framework guide for more details.

Build image policies for Workers Builds and Cloudflare Pages

We've published build image policies for Workers Builds and Cloudflare Pages, which establish:

  • Minor version updates: We typically update preinstalled software to the latest available minor version without notice. For tools that don't follow semantic versioning (e.g., Bun or Hugo), we provide 3 months’ notice.
  • Major version updates: Before preinstalled software reaches end-of-life, we update to the next stable LTS version with 3 months’ notice.
  • Build image version deprecation (Pages only): We provide 6 months’ notice before deprecation. Projects on v1 or v2 will be automatically moved to v3 on their specified deprecation dates.

To prepare for updates, monitor the Cloudflare Changelog ↗︎, dashboard notifications, and email. You can also override default versions to maintain specific versions.

Retrieve your authentication token with `wrangler auth token`

Wrangler now includes a new wrangler auth token command that retrieves your current authentication token or credentials for use with other tools and scripts.

wrangler auth token

The command returns whichever authentication method is currently configured, in priority order: API token from CLOUDFLARE_API_TOKEN, or OAuth token from wrangler login (automatically refreshed if expired).

Use the --json flag to get structured output including the token type:

wrangler auth token --json

The JSON output includes the authentication type:

// API token
{ "type": "api_token", "token": "..." }

// OAuth token
{ "type": "oauth", "token": "..." }

// API key/email (only available with --json)
{ "type": "api_key", "key": "...", "email": "..." }

API key/email credentials from CLOUDFLARE_API_KEY and CLOUDFLARE_EMAIL require the --json flag since this method uses two values instead of a single token.

Support for ctx.exports in @cloudflare/vitest-pool-workers

The @cloudflare/vitest-pool-workers package now supports the ctx.exports API, allowing you to access your Worker's top-level exports during tests.

You can access ctx.exports in unit tests by calling createExecutionContext():

import { createExecutionContext } from "cloudflare:test";
import { it, expect } from "vitest";

it("can access ctx.exports", async () => {
  const ctx = createExecutionContext();
  const result = await ctx.exports.MyEntryPoint.myMethod();
  expect(result).toBe("expected value");
});

Alternatively, you can import exports directly from cloudflare:workers:

import { exports } from "cloudflare:workers";
import { it, expect } from "vitest";

it("can access imported exports", async () => {
  const result = await exports.MyEntryPoint.myMethod();
  expect(result).toBe("expected value");
});

See the context-exports fixture ↗︎ for a complete example.

Configure your framework for Cloudflare automatically

Wrangler now supports automatic configuration for popular web frameworks in experimental mode, making it even easier to deploy to Cloudflare Workers.

Previously, if you wanted to deploy an application using a popular web framework like Next.js or Astro, you had to follow tutorials to set up your application for deployment to Cloudflare Workers. This usually involved creating a Wrangler file, installing adapters, or changing configuration options.

Now wrangler deploy does this for you. Starting with Wrangler 4.55, you can use npx wrangler deploy --x-autoconfig in the directory of any web application using one of the supported frameworks. Wrangler will then proceed to configure and deploy it to your Cloudflare account.

You can also configure your application without deploying it by using the new npx wrangler setup command. This enables you to easily review what changes we are making so your application is ready for Cloudflare Workers.

The following application frameworks are supported starting today:

  • Next.js
  • Astro
  • Nuxt
  • TanStack Start
  • SolidStart
  • React Router
  • SvelteKit
  • Docusaurus
  • Qwik
  • Analog

Automatic configuration also supports static sites by detecting the assets directory and build command. From a single index.html file to the output of a generator like Jekyll or Hugo, you can just run npx wrangler deploy --x-autoconfig to upload to Cloudflare.

We're really excited to bring you automatic configuration so you can do more with Workers. Please let us know if you run into challenges using this experimentally. We’ve opened a GitHub discussion ↗︎ and would love to hear your feedback.

Python cold start improvements

Python Workers now feature improved cold start performance, reducing initialization time for new Worker instances. This improvement is particularly noticeable for Workers with larger dependency sets or complex initialization logic.

Every time you deploy a Python Worker, a memory snapshot is captured after the top level of the Worker is executed. This snapshot captures all imports, including package imports that are often costly to load. The memory snapshot is loaded when the Worker is first started, avoiding the need to reload the Python runtime and all dependencies on each cold start.

We set up a benchmark that imports common packages (httpx ↗︎, fastapi ↗︎ and pydantic ↗︎) to see how Python Workers stack up against other platforms:

Platform Mean Cold Start (ms)
Cloudflare Python Workers 1027
AWS Lambda 2502
Google Cloud Run 3069

These benchmarks run continuously. You can view the results and the methodology on our benchmark page ↗︎.

In additional testing, we have found that without any memory snapshot, the cold start for this benchmark takes around 10 seconds, so this change improves cold start performance by roughly a factor of 10.

To get started with Python Workers, check out our Python Workers overview.

Easy Python package management with Pywrangler

We are introducing a brand new tool called Pywrangler, which simplifies package management in Python Workers by automatically installing Workers-compatible Python packages into your project.

With Pywrangler, you specify your Worker's Python dependencies in your pyproject.toml file:

[project]
name = "python-beautifulsoup-worker"
version = "0.1.0"
description = "A simple Worker using beautifulsoup4"
requires-python = ">=3.12"
dependencies = [
    "beautifulsoup4"
]

[dependency-groups]
dev = [
  "workers-py",
  "workers-runtime-sdk"
]

You can then develop and deploy your Worker using the following commands:

uv run pywrangler dev
uv run pywrangler deploy

Pywrangler automatically downloads and vendors the necessary packages for your Worker, and these packages are bundled with the Worker when you deploy.

Consult the Python packages documentation for full details on Pywrangler and Python package management in Workers.

Wrangler config is optional when using Vite plugin

When using the Cloudflare Vite plugin to build and deploy Workers, a Wrangler configuration file is now optional for assets-only (static) sites. If no wrangler.toml, wrangler.json, or wrangler.jsonc file is found, the plugin generates sensible defaults for an assets-only site. The name is based on the package.json or the project directory name, and the compatibility_date uses the latest date supported by your installed Miniflare version.

This allows easier setup for static sites using Vite. Note that SPAs will still need to set assets.not_found_handling to single-page-application ↗︎ in order to function correctly.

Configure Workers programmatically using the Vite plugin

The Cloudflare Vite plugin now supports programmatic configuration of Workers without a Wrangler configuration file. You can use the config option to define Worker settings directly in your Vite configuration, or to modify existing configuration loaded from a Wrangler config file. This is particularly useful when integrating with other build tools or frameworks, as it allows them to control Worker configuration without needing users to manage a separate config file.

The config option

The Vite plugin's new config option accepts either a partial configuration object or a function that receives the current configuration and returns overrides. This option is applied after any config file is loaded, allowing the plugin to override specific values or define Worker configuration entirely in code.

Example usage

Setting config to an object to provide configuration values that merge with defaults and config file settings:

vite.config.tsts
import { defineConfig } from "vite";
import { cloudflare } from "@cloudflare/vite-plugin";

export default defineConfig({
	plugins: [
		cloudflare({
			config: {
				name: "my-worker",
				compatibility_flags: ["nodejs_compat"],
				send_email: [
					{
						name: "EMAIL",
					},
				],
			},
		}),
	],
});

Use a function to modify the existing configuration:

vite.config.tsts
import { defineConfig } from "vite";
import { cloudflare } from "@cloudflare/vite-plugin";
export default defineConfig({
	plugins: [
		cloudflare({
			config: (userConfig) => {
				delete userConfig.compatibility_flags;
			},
		}),
	],
});

Return an object with values to merge:

vite.config.tsts
import { defineConfig } from "vite";
import { cloudflare } from "@cloudflare/vite-plugin";

export default defineConfig({
	plugins: [
		cloudflare({
			config: (userConfig) => {
				if (!userConfig.compatibility_flags.includes("no_nodejs_compat")) {
					return { compatibility_flags: ["nodejs_compat"] };
				}
			},
		}),
	],
});

Auxiliary Workers

Auxiliary Workers also support the config option, enabling multi-Worker architectures without config files.

Define auxiliary Workers without config files using config inside the auxiliaryWorkers array:

vite.config.tsts
import { defineConfig } from "vite";
import { cloudflare } from "@cloudflare/vite-plugin";

export default defineConfig({
	plugins: [
		cloudflare({
			config: {
				name: "entry-worker",
				main: "./src/entry.ts",
				services: [{ binding: "API", service: "api-worker" }],
			},
			auxiliaryWorkers: [
				{
					config: {
						name: "api-worker",
						main: "./src/api.ts",
					},
				},
			],
		}),
	],
});

For more details and examples, see Programmatic configuration.

One-click Access protection for Workers now creates reusable Cloudflare Access policies

Workers applications now use reusable Cloudflare Access policies to reduce duplication and simplify access management across multiple Workers.

Previously, enabling Cloudflare Access on a Worker created per-application policies, unique to each application. Now, we create reusable policies that can be shared across applications:

  • Preview URLs: All Workers preview URLs share a single "Cloudflare Workers Preview URLs" policy across your account. This policy is automatically created the first time you enable Access on any preview URL. By sharing a single policy across all preview URLs, you can configure access rules once and have them apply company-wide to all Workers which protect preview URLs. This makes it much easier to manage who can access preview environments without having to update individual policies for each Worker.

  • Production workers.dev URLs: When enabled, each Worker gets its own reusable policy (named <worker-name> - Production) by default. We recognize production services often have different access requirements and having individual policies here makes it easier to configure service-to-service authentication or protect internal dashboards or applications with specific user groups. Keeping these policies separate gives you the flexibility to configure exactly the right access rules for each production service. When you disable Access on a production Worker, the associated policy is automatically cleaned up if it's not being used by other applications.

This change reduces policy duplication, simplifies cross-company access management for preview environments, and provides the flexibility needed for production services. You can still customize access rules by editing the reusable policies in the Zero Trust dashboard.

To enable Cloudflare Access on your Worker:

  1. In the Cloudflare dashboard, go to Workers & Pages.
  2. Select your Worker.
  3. Go to Settings > Domains & Routes.
  4. For workers.dev or Preview URLs, click Enable Cloudflare Access.
  5. Optionally, click Manage Cloudflare Access to customize the policy.

For more information on configuring Cloudflare Access for Workers, refer to the Workers Access documentation.

Better local deployment flow for Cloudflare Workers

Until now, if a Worker had been previously deployed via the Cloudflare Dashboard ↗︎, a subsequent deployment done via the Cloudflare Workers CLI, Wrangler (through the deploy command), would allow the user to override the Worker's dashboard settings without providing details on what dashboard settings would be lost.

Now instead, wrangler deploy presents a helpful representation of the differences between the local configuration and the remote dashboard settings, and offers to update your local configuration file for you.

See example below showing a before and after for wrangler deploy when a local configuration is expected to override a Worker's dashboard settings:

Before

wrangler deploy run before the improved workflow

After

wrangler deploy run after the improved workflow

Also, if instead Wrangler detects that a deployment would override remote dashboard settings but in an additive way, without modifying or removing any of them, it will simply proceed with the deployment without requesting any user interaction.

Update to Wrangler v4.50.0 or greater to take advantage of this improved deploy flow.

More SQL aggregate, date and time functions available in Workers Analytics Engine

You can now perform more powerful queries directly in Workers Analytics Engine ↗︎ with a major expansion of our SQL function library.

Workers Analytics Engine allows you to ingest and store high-cardinality data at scale (such as custom analytics) and query your data through a simple SQL API.

Today, we've expanded Workers Analytics Engine's SQL capabilities with several new functions:

New aggregate functions: ↗︎

  • countIf() - count the number of rows which satisfy a provided condition
  • sumIf() - calculate a sum from rows which satisfy a provided condition
  • avgIf() - calculate an average from rows which satisfy a provided condition

New date and time functions: ↗︎

  • toYear()
  • toMonth()
  • toDayOfMonth()
  • toDayOfWeek()
  • toHour()
  • toMinute()
  • toSecond()
  • toStartOfYear()
  • toStartOfMonth()
  • toStartOfWeek()
  • toStartOfDay()
  • toStartOfHour()
  • toStartOfFifteenMinutes()
  • toStartOfTenMinutes()
  • toStartOfFiveMinutes()
  • toStartOfMinute()
  • today()
  • toYYYYMM()

Ready to get started?

Whether you're building usage-based billing systems, customer analytics dashboards, or other custom analytics, these functions let you get the most out of your data. Get started with Workers Analytics Engine and explore all available functions in our SQL reference documentation.

cloudflared proxy-dns command will be removed starting February 2, 2026

Starting February 2, 2026, the cloudflared proxy-dns command will be removed from all new cloudflared releases.

This change is being made to enhance security and address a potential vulnerability in an underlying DNS library. This vulnerability is specific to the proxy-dns command and does not affect any other cloudflared features, such as the core Cloudflare Tunnel service.

The proxy-dns command, which runs a client-side DNS-over-HTTPS (DoH) proxy, has been an officially undocumented feature for several years. This functionality is fully and securely supported by our actively developed products.

Versions of cloudflared released before this date will not be affected and will continue to operate. However, note that our official support policy for any cloudflared release is one year from its release date.

Migration paths

We strongly advise users of this undocumented feature to migrate to one of the following officially supported solutions before February 2, 2026, to continue benefiting from secure DNS-over-HTTPS.

End-user devices

The preferred method for enabling DNS-over-HTTPS on user devices is the Cloudflare WARP client. The WARP client automatically secures and proxies all DNS traffic from your device, integrating it with your organization's Zero Trust policies and posture checks.

Servers, routers, and IoT devices

For scenarios where installing a client on every device is not possible (such as servers, routers, or IoT devices), we recommend using the WARP Connector.

Instead of running cloudflared proxy-dns on a machine, you can install the WARP Connector on a single Linux host within your private network. This connector will act as a gateway, securely routing all DNS and network traffic from your entire subnet to Cloudflare for filtering and logging.

Select Wrangler environments using the CLOUDFLARE_ENV environment variable

Wrangler now supports using the CLOUDFLARE_ENV environment variable to select the active environment for your Worker commands. This provides a more flexible way to manage environments, especially when working with build tools and CI/CD pipelines.

What's new

Environment selection via environment variable:

  • Set CLOUDFLARE_ENV to specify which environment to use for Wrangler commands
  • Works with all Wrangler commands that support the --env flag
  • The --env command line argument takes precedence over the CLOUDFLARE_ENV environment variable

Example usage

# Deploy to the production environment using CLOUDFLARE_ENV
CLOUDFLARE_ENV=production wrangler deploy

# Upload a version to the staging environment
CLOUDFLARE_ENV=staging wrangler versions upload

# The --env flag takes precedence over CLOUDFLARE_ENV
CLOUDFLARE_ENV=dev wrangler deploy --env production
# This will deploy to production, not dev

Use with build tools

The CLOUDFLARE_ENV environment variable is particularly useful when working with build tools like Vite. You can set the environment once during the build process, and it will be used for both building and deploying your Worker:

# Set the environment for both build and deploy
CLOUDFLARE_ENV=production npm run build & wrangler deploy

When using @cloudflare/vite-plugin, the build process generates a "redirected deploy config" that is flattened to only contain the active environment. Wrangler will validate that the environment specified matches the environment used during the build to prevent accidentally deploying a Worker built for one environment to a different environment.

Learn more

Workers automatic tracing, now in open beta

Enable automatic tracing on your Workers, giving you detailed metadata and timing information for every operation your Worker performs.

Tracing example

Tracing helps you identify performance bottlenecks, resolve errors, and understand how your Worker interacts with other services on the Workers platform. You can now answer questions like:

  • Which calls are slowing down my application?
  • Which queries to my database take the longest?
  • What happened within a request that resulted in an error?

You can now:

To get started, set:

{
	"observability": {
		"traces": {
			"enabled": true,
		},
	},
}

Want to learn more?

Capture Wrangler command output in structured format

You can now capture Wrangler command output in a structured ND-JSON ↗︎ format by setting the WRANGLER_OUTPUT_FILE_PATH or WRANGLER_OUTPUT_FILE_DIRECTORY environment variables. This feature is particularly useful for CI/CD pipelines and automation tools that need programmatic access to deployment information such as worker names, version IDs, deployment URLs, and error details. Commands that support this feature include wrangler deploy, wrangler versions upload, wrangler versions deploy, and wrangler pages deploy.

Access Workers preview URLs from the Build details page

You can now access preview URLs directly from the build details page, making it easier to test your changes when reviewing builds in the dashboard.

preview button

What's new

  • A Preview button now appears in the top-right corner of the build details page for successful builds
  • Click it to instantly open the latest preview URL
  • Matches the same experience you're familiar with from Pages

Automatic resource provisioning for KV, R2, and D1

Previously, if you wanted to develop or deploy a worker with attached resources, you'd have to first manually create the desired resources. Now, if your Wrangler configuration file includes a KV namespace, D1 database, or R2 bucket that does not yet exist on your account, you can develop locally and deploy your application seamlessly, without having to run additional commands.

Automatic provisioning is launching as an open beta, and we'd love to hear your feedback to help us make improvements! It currently works for KV, R2, and D1 bindings. You can disable the feature using the --no-x-provision flag.

To use this feature, update to wrangler@4.45.0 and add bindings to your config file without resource IDs e.g.:

{
	"kv_namespaces": [{ "binding": "MY_KV" }],
	"d1_databases": [{ "binding": "MY_DB" }],
	"r2_buckets": [{ "binding": "MY_R2" }],
}

wrangler dev will then automatically create these resources for you locally, and on your next run of wrangler deploy, Wrangler will call the Cloudflare API to create the requested resources and link them to your Worker.

Though resource IDs will be automatically written back to your Wrangler config file after resource creation, resources will stay linked across future deploys even without adding the resource IDs to the config file. This is especially useful for shared templates, which now no longer need to include account-specific resource IDs when adding a binding.

Build TanStack Start apps with the Cloudflare Vite plugin

The Cloudflare Vite plugin now supports TanStack Start ↗︎ apps. Get started with new or existing projects.

New projects

Create a new TanStack Start project that uses the Cloudflare Vite plugin via the create-cloudflare CLI:

npm create cloudflare@latest -- my-tanstack-start-app --framework=tanstack-start

Existing projects

Migrate an existing TanStack Start project to use the Cloudflare Vite plugin:

  1. Install @cloudflare/vite-plugin and wrangler
npm i -D @cloudflare/vite-plugin wrangler
  1. Add the Cloudflare plugin to your Vite config
vite.config.tsts
import { defineConfig } from "vite";
import { tanstackStart } from "@tanstack/react-start/plugin/vite";
import viteReact from "@vitejs/plugin-react";
import { cloudflare } from "@cloudflare/vite-plugin";

export default defineConfig({
	plugins: [
		cloudflare({ viteEnvironment: { name: "ssr" } }),
		tanstackStart(),
		viteReact(),
	],
});
  1. Add your Worker config file
{
	"$schema": "./node_modules/wrangler/config-schema.json",
	"name": "my-tanstack-start-app",
	// Set this to today's date
	"compatibility_date": "2026-10-11",
	"compatibility_flags": [
		"nodejs_compat"
	],
	"main": "@tanstack/react-start/server-entry"
}
"$schema" = "./node_modules/wrangler/config-schema.json"
name = "my-tanstack-start-app"
# Set this to today's date
compatibility_date = "2026-10-11"
compatibility_flags = [ "nodejs_compat" ]
main = "@tanstack/react-start/server-entry"
  1. Modify the scripts in your package.json
package.jsonjson
{
	"scripts": {
		"dev": "vite dev",
		"build": "vite build && tsc --noEmit",
		"start": "node .output/server/index.mjs",
		"preview": "vite preview",
		"deploy": "npm run build && wrangler deploy",
		"cf-typegen": "wrangler types"
	}
}

See the TanStack Start framework guide for more info.

Workers Preview URL default behavior now matches your workers.dev setting

We have updated the default behavior for Cloudflare Workers Preview URLs. Going forward, if a preview URL setting is not explicitly configured during deployment, its default behavior will automatically match the setting of your workers.dev subdomain.

This change is intended to provide a more intuitive and secure experience by aligning your preview URL's default state with your workers.dev configuration to prevent cases where a preview URL might remain public even after you disabled your workers.dev route.

What this means for you:

  • If neither setting is configured: both the workers.dev route and the preview URL will default to enabled
  • If your workers.dev route is enabled and you do not explicitly set Preview URLs to enabled or disabled: Preview URLs will default to enabled
  • If your workers.dev route is disabled and you do not explicitly set Preview URLs to enabled or disabled: Preview URLs will default to disabled

You can override the default setting by explicitly enabling or disabling the preview URL in your Worker's configuration through the API, Dashboard, or Wrangler.

Wrangler Version Behavior

The default behavior depends on the version of Wrangler you are using. This new logic applies to the latest version. Here is a summary of the behavior across different versions:

  • Before v4.34.0: Preview URLs defaulted to enabled, regardless of the workers.dev setting.
  • v4.34.0 up to (but not including) v4.44.0: Preview URLs defaulted to disabled, regardless of the workers.dev setting.
  • v4.44.0 or later: Preview URLs now default to matching your workers.dev setting.

Why we’re making this change

In July, we introduced preview URLs to Workers, which let you preview code changes before deploying to production. This made disabling your Worker’s workers.dev URL an ambiguous action — the preview URL, served as a subdomain of workers.dev (ex: preview-id-worker-name.account-name.workers.dev) would still be live even if you had disabled your Worker’s workers.dev route. If you misinterpreted what it meant to disable your workers.dev route, you might unintentionally leave preview URLs enabled when you didn’t mean to, and expose them to the public Internet.

To address this, we made a one-time update to disable preview URLs on existing Workers that had their workers.dev route disabled and changed the default behavior to be disabled for all new deployments where a preview URL setting was not explicitly configured.

While this change helped secure many customers, it was disruptive for customers who keep their workers.dev route enabled and actively use the preview functionality, as it now required them to explicitly enable preview URLs on every redeployment.This new, more intuitive behavior ensures that your preview URL settings align with your workers.dev configuration by default, providing a more secure and predictable experience.

Securing access to workers.dev and preview URL endpoints

To further secure your workers.dev subdomain and preview URL, you can enable Cloudflare Access with a single click in your Worker's settings to limit access to specific users or groups.

Worker startup time limit increased to 1 second

You can now upload a Worker that takes up 1 second to parse and execute its global scope. Previously, startup time was limited to 400 ms.

This allows you to run Workers that import more complex packages and execute more code prior to requests being handled.

For more information, see the documentation on Workers startup limits.