Changelog

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

After

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.

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()

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.

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.

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

# 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

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.

• System environment variables
• Environments

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

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:

• View traces alongside your logs in the Workers Observability dashboard
• Export traces (and correlated logs) to any OTLP-compatible destination ↗, such as Honeycomb, Sentry or Grafana, by configuring a tracing destination in the Cloudflare dashboard ↗
• Analyze and query across span attributes (operation type, status, duration, errors)

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

• Read the announcement ↗
• Check out the documentation

You can now set a jurisdiction when creating a D1 database to guarantee where your database runs and stores data. Jurisdictions can help you comply with data localization regulations such as GDPR. Supported jurisdictions include eu and fedramp.

A jurisdiction can only be set at database creation time via wrangler, REST API or the UI and cannot be added/updated after the database already exists.

npx wrangler@latest d1 create db-with-jurisdiction --jurisdiction eu

curl -X POST "https://api.cloudflare.com/client/v4/accounts/<account_id>/d1/database" \
     -H "Authorization: Bearer $TOKEN" \
     -H "Content-Type: application/json" \
     --data '{"name": "db-with-jurisdiction", "jurisdiction": "eu" }'

To learn more, visit D1's data location documentation.

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.

Workers, including those using Durable Objects and Browser Rendering, may now process WebSocket messages up to 32 MiB in size. Previously, this limit was 1 MiB.

This change allows Workers to handle use cases requiring large message sizes, such as processing Chrome Devtools Protocol messages.

For more information, please see the Durable Objects startup limits.

We've raised the Cloudflare Workflows account-level limits for all accounts on the Workers paid plan:

• Instance creation rate increased from 100 workflow instances per 10 seconds to 100 instances per second
• Concurrency limit increased from 4,500 to 10,000 workflow instances per account

These increases mean you can create new instances up to 10x faster, and have more workflow instances concurrently executing. To learn more and get started with Workflows, refer to the getting started guide.

If your application requires a higher limit, fill out the Limit Increase Request Form or contact your account team. Please refer to Workflows pricing for more information.

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.

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

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.

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

yarn create cloudflare my-tanstack-start-app --framework=tanstack-start

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

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

yarn add -D @cloudflare/vite-plugin wrangler

pnpm add -D @cloudflare/vite-plugin wrangler

bun add -d @cloudflare/vite-plugin wrangler

2. Add the Cloudflare plugin to your Vite config

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(),
	],
});

3. 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": "2026-07-27",
	"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 = "2026-07-27"
compatibility_flags = [ "nodejs_compat" ]
main = "@tanstack/react-start/server-entry"

4. Modify the scripts in your package.json

{
	"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.

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.

You can now view and write to each Durable Object's storage using a UI editor on the Cloudflare dashboard. Only Durable Objects using SQLite storage can use Data Studio.

Data Studio unlocks easier data access with Durable Objects for prototyping application data models to debugging production storage usage. Before, querying your Durable Objects data required deploying a Worker.

To access a Durable Object, you can provide an object's unique name or ID generated by Cloudflare. Data Studio requires you to have at least the Workers Platform Admin role, and all queries are captured with audit logging for your security and compliance needs. Queries executed by Data Studio send requests to your remote, deployed objects and incur normal usage billing.

To learn more, visit the Data Studio documentation. If you have feedback or suggestions for the new Data Studio, please share your experience on Discord ↗

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.

You can now upload Workers with static assets (like HTML, CSS, JavaScript, images) with the Cloudflare Terraform provider v5.11.0 ↗, making it even easier to deploy and manage full-stack apps with IaC.

Previously, you couldn't use Terraform to upload static assets without writing custom scripts to handle generating an asset manifest, calling the Cloudflare API to upload assets in chunks, and handling change detection.

Now, you simply define the directory where your assets are built, and we handle the rest. Check out the examples for what this looks like in Terraform configuration.

You can get started today with the Cloudflare Terraform provider (v5.11.0) ↗, using either the existing cloudflare_workers_script resource ↗, or the beta cloudflare_worker_version resource ↗.

Here's how you can use the existing cloudflare_workers_script ↗ resource to upload your Worker code and assets in one shot.

resource "cloudflare_workers_script" "my_app" {
  account_id  = var.account_id
  script_name = "my-app"

  content_file   = "./dist/worker/index.js"
  content_sha256 = filesha256("./dist/worker/index.js")
  main_module    = "index.js"

  # Just point to your assets directory - that's it!
  assets = {
    directory = "./dist/static"
  }
}

And here's an example using the beta cloudflare_worker_version ↗ resource, alongside the cloudflare_worker ↗ and cloudflare_workers_deployment ↗ resources:

# This tracks the existence of your Worker, so that you
# can upload code and assets separately from tracking Worker state.

resource "cloudflare_worker" "my_app" {
  account_id = var.account_id
  name       = "my-app"
}

resource "cloudflare_worker_version" "my_app_version" {
  account_id = var.account_id
  worker_id  = cloudflare_worker.my_app.id

  # Just point to your assets directory - that's it!
  assets = {
    directory = "./dist/static"
  }

  modules = [{
    name         = "index.js"
    content_file = "./dist/worker/index.js"
    content_type = "application/javascript+module"
  }]
}

resource "cloudflare_workers_deployment" "my_app_deployment" {
  account_id  = var.account_id
  script_name = cloudflare_worker.my_app.name

  strategy = "percentage"
  versions = [{
    version_id = cloudflare_worker_version.my_app_version.id
    percentage = 100
  }]
}

Under the hood, the Cloudflare Terraform provider now handles the same logic that Wrangler uses for static asset uploads. This includes scanning your assets directory, computing hashes for each file, generating a manifest with file metadata, and calling the Cloudflare API to upload any missing files in chunks. We support large directories with parallel uploads and chunking, and when the asset manifest hash changes, we detect what's changed and trigger an upload for only those changed files.

• Get started with the Cloudflare Terraform provider (v5.11.0) ↗
• You can use either the existing cloudflare_workers_script resource ↗ to upload your Worker code and assets in one resource.
• Or you can use the new beta cloudflare_worker_version resource ↗ (along with the cloudflare_worker ↗ and cloudflare_workers_deployment ↗) resources to more granularly control the lifecycle of each Worker resource.

You can now create and manage Workflows using Terraform, now supported in the Cloudflare Terraform provider v5.11.0 ↗. Workflows allow you to build durable, multi-step applications -- without needing to worry about retrying failed tasks or managing infrastructure.

Now, you can deploy and manage Workflows through Terraform using the new cloudflare_workflow resource ↗:

resource "cloudflare_workflow" "my_workflow" {
  account_id    = var.account_id
  workflow_name = "my-workflow"
  class_name    = "MyWorkflow"
  script_name   = "my-worker"
}

Here are full examples of how to configure cloudflare_workflow in Terraform, using the existing cloudflare_workers_script resource ↗, and the beta cloudflare_worker_version resource ↗.

resource "cloudflare_workers_script" "workflow_worker" {
  account_id  = var.cloudflare_account_id
  script_name = "my-workflow-worker"

  content_file   = "${path.module}/../dist/worker/index.js"
  content_sha256 = filesha256("${path.module}/../dist/worker/index.js")
  main_module    = "index.js"
}

resource "cloudflare_workflow" "workflow" {
  account_id    = var.cloudflare_account_id
  workflow_name = "my-workflow"
  class_name    = "MyWorkflow"
  script_name   = cloudflare_workers_script.workflow_worker.script_name
}

You can more granularly control the lifecycle of each Worker resource using the beta cloudflare_worker_version ↗ resource, alongside the cloudflare_worker ↗ and cloudflare_workers_deployment ↗ resources.

resource "cloudflare_worker" "workflow_worker" {
  account_id = var.cloudflare_account_id
  name       = "my-workflow-worker"
}

resource "cloudflare_worker_version" "workflow_worker_version" {
  account_id = var.cloudflare_account_id
  worker_id  = cloudflare_worker.workflow_worker.id

  main_module         = "index.js"

  modules = [{
    name         = "index.js"
    content_file = "${path.module}/../dist/worker/index.js"
    content_type = "application/javascript+module"
  }]
}

resource "cloudflare_workers_deployment" "workflow_deployment" {
  account_id  = var.cloudflare_account_id
  script_name = cloudflare_worker.workflow_worker.name

  strategy = "percentage"
  versions = [{
    version_id = cloudflare_worker_version.workflow_worker_version.id
    percentage = 100
  }]
}

resource "cloudflare_workflow" "my_workflow" {
  account_id    = var.cloudflare_account_id
  workflow_name = "my-workflow"
  class_name    = "MyWorkflow"
  script_name   = cloudflare_worker.workflow_worker.name
}

• Get started with the Cloudflare Terraform provider (v5.11.0) ↗ and the new cloudflare_workflow resource ↗.

Each of your Workers now has a new overview page in the Cloudflare dashboard.

The goal is to make it easier to understand your Worker without digging through multiple tabs. Think of it as a new home base, a place to get a high-level overview on what's going on.

It's the first place you land when you open a Worker in the dashboard, and it gives you an immediate view of what’s going on. You can see requests, errors, and CPU time at a glance. You can view and add bindings, and see recent versions of your app, including who published them.

Navigation is also simpler, with visually distinct tabs at the top of the page. At the bottom right you'll find guided steps for what to do next that are based on the state of your Worker, such as adding a binding or connecting a custom domain.

We plan to add more here over time. Better insights, more controls, and ways to manage your Worker from one page.

If you have feedback or suggestions for the new Overview page or your Cloudflare Workers experience in general, we'd love to hear from you. Join the Cloudflare developer community on Discord ↗.

You can now enable Cloudflare Access for your workers.dev and Preview URLs in a single click.

Access allows you to limit access to your Workers to specific users or groups. You can limit access to yourself, your teammates, your organization, or anyone else you specify in your Access policy.

To enable Cloudflare Access:

1. In the Cloudflare dashboard, go to the Workers & Pages page.

   Go to Workers & Pages ↗

2. In Overview, select your Worker.

3. Go to Settings > Domains & Routes.

4. For workers.dev or Preview URLs, click Enable Cloudflare Access.

5. Optionally, to configure the Access application, click Manage Cloudflare Access. There, you can change the email addresses you want to authorize. View Access policies to learn about configuring alternate rules.

To fully secure your application, it is important that you validate the JWT that Cloudflare Access adds to the Cf-Access-Jwt-Assertion header on the incoming request.

The following code will validate the JWT using the jose NPM package ↗:

import { jwtVerify, createRemoteJWKSet } from "jose";

export default {
	async fetch(request, env, ctx) {
		// Verify the POLICY_AUD environment variable is set
		if (!env.POLICY_AUD) {
			return new Response("Missing required audience", {
				status: 403,
				headers: { "Content-Type": "text/plain" },
			});
		}

		// Get the JWT from the request headers
		const token = request.headers.get("cf-access-jwt-assertion");

		// Check if token exists
		if (!token) {
			return new Response("Missing required CF Access JWT", {
				status: 403,
				headers: { "Content-Type": "text/plain" },
			});
		}

		try {
			// Create JWKS from your team domain
			const JWKS = createRemoteJWKSet(
				new URL(`${env.TEAM_DOMAIN}/cdn-cgi/access/certs`),
			);

			// Verify the JWT
			const { payload } = await jwtVerify(token, JWKS, {
				issuer: env.TEAM_DOMAIN,
				audience: env.POLICY_AUD,
			});

			// Token is valid, proceed with your application logic
			return new Response(`Hello ${payload.email || "authenticated user"}!`, {
				headers: { "Content-Type": "text/plain" },
			});
		} catch (error) {
			// Token verification failed
			return new Response(`Invalid token: ${error.message}`, {
				status: 403,
				headers: { "Content-Type": "text/plain" },
			});
		}
	},
};

Add these environment variables to your Worker:

• POLICY_AUD: Your application's AUD tag
• TEAM_DOMAIN: https://<your-team-name>.cloudflareaccess.com

Both of these appear in the modal that appears when you enable Cloudflare Access.

You can set these variables by adding them to your Worker's Wrangler configuration file, or via the Cloudflare dashboard under Workers & Pages > your-worker > Settings > Environment Variables.

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: ↗

• argMin() - Returns the value associated with the minimum in a group
• argMax() - Returns the value associated with the maximum in a group
• topK() - Returns an array of the most frequent values in a group
• topKWeighted() - Returns an array of the most frequent values in a group using weights
• first_value() - Returns the first value in an ordered set of values within a partition
• last_value() - Returns the last value in an ordered set of values within a partition

New bit functions: ↗

• bitAnd() - Returns the bitwise AND of two expressions
• bitCount() - Returns the number of bits set to one in the binary representation of a number
• bitHammingDistance() - Returns the number of bits that differ between two numbers
• bitNot() - Returns a number with all bits flipped
• bitOr() - Returns the inclusive bitwise OR of two expressions
• bitRotateLeft() - Rotates all bits in a number left by specified positions
• bitRotateRight() - Rotates all bits in a number right by specified positions
• bitShiftLeft() - Shifts all bits in a number left by specified positions
• bitShiftRight() - Shifts all bits in a number right by specified positions
• bitTest() - Returns the value of a specific bit in a number
• bitXor() - Returns the bitwise exclusive-or of two expressions

New mathematical functions: ↗

• abs() - Returns the absolute value of a number
• log() - Computes the natural logarithm of a number
• round() - Rounds a number to a specified number of decimal places
• ceil() - Rounds a number up to the nearest integer
• floor() - Rounds a number down to the nearest integer
• pow() - Returns a number raised to the power of another number

New string functions: ↗

• lowerUTF8() - Converts a string to lowercase using UTF-8 encoding
• upperUTF8() - Converts a string to uppercase using UTF-8 encoding

New encoding functions: ↗

• hex() - Converts a number to its hexadecimal representation
• bin() - Converts a string to its binary representation

New type conversion functions: ↗

• toUInt8() - Converts any numeric expression, or expression resulting in a string representation of a decimal, into an unsigned 8 bit integer

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.

The ctx.exports API contains automatically-configured bindings corresponding to your Worker's top-level exports. For each top-level export extending WorkerEntrypoint, ctx.exports will contain a Service Binding by the same name, and for each export extending DurableObject (and for which storage has been configured via a migration), ctx.exports will contain a Durable Object namespace binding. This means you no longer have to configure these bindings explicitly in wrangler.jsonc/wrangler.toml.

Example:

import { WorkerEntrypoint } from "cloudflare:workers";

export class Greeter extends WorkerEntrypoint {
  greet(name) {
    return `Hello, ${name}!`;
  }
}

export default {
  async fetch(request, env, ctx) {
    let greeting = await ctx.exports.Greeter.greet("World")
    return new Response(greeting);
  }
}

At present, you must use the enable_ctx_exports compatibility flag to enable this API, though it will be on by default in the future.

See the API reference for more information.

You can run multiple Workers in a single dev command by passing multiple config files to wrangler dev:

wrangler dev --config ./web/wrangler.jsonc --config ./api/wrangler.jsonc

Previously, if you ran the command above and then also ran wrangler dev for a different Worker, the Workers running in separate wrangler dev sessions could not communicate with each other. This prevented you from being able to use Service Bindings ↗ and Tail Workers ↗ in local development, when running separate wrangler dev sessions.

Now, the following works as expected:

# Terminal 1: Run your application that includes both Web and API workers
wrangler dev --config ./web/wrangler.jsonc --config ./api/wrangler.jsonc

# Terminal 2: Run your auth worker separately
wrangler dev --config ./auth/wrangler.jsonc

These Workers can now communicate with each other across separate dev commands, regardless of your development setup.

export default {
	async fetch(request, env) {
		// This service binding call now works across dev commands
		const authorized = await env.AUTH.isAuthorized(request);

		if (!authorized) {
			return new Response("Unauthorized", { status: 401 });
		}

		return new Response("Hello from API Worker!", { status: 200 });
	},
};

Check out the Developing with multiple Workers guide to learn more about the different approaches and when to use each one.

Rate Limiting within Cloudflare Workers is now Generally Available (GA).

The ratelimit binding is now stable and recommended for all production workloads. Existing deployments using the unsafe binding will continue to function to allow for a smooth transition.

For more details, refer to Workers Rate Limiting documentation.

In workers-rs ↗, Rust panics were previously non-recoverable. A panic would put the Worker into an invalid state, and further function calls could result in memory overflows or exceptions.

Now, when a panic occurs, in-flight requests will throw 500 errors, but the Worker will automatically and instantly recover for future requests.

This ensures more reliable deployments. Automatic panic recovery is enabled for all new workers-rs deployments as of version 0.6.5, with no configuration required.

Rust Workers are built with Wasm Bindgen, which treats panics as non-recoverable. After a panic, the entire Wasm application is considered to be in an invalid state.

We now attach a default panic handler in Rust:

std::panic::set_hook(Box::new(move |panic_info| {
  hook_impl(panic_info);
}));

Which is registered by default in the JS initialization:

import { setPanicHook } from "./index.js";
setPanicHook(function (err) {
	console.error("Panic handler!", err);
});

When a panic occurs, we reset the Wasm state to revert the Wasm application to how it was when the application started.

We worked upstream on the Wasm Bindgen project to implement a new --experimental-reset-state-function compilation option ↗ which outputs a new __wbg_reset_state function.

This function clears all internal state related to the Wasm VM, and updates all function bindings in place to reference the new WebAssembly instance.

One other necessary change here was associating Wasm-created JS objects with an instance identity. If a JS object created by an earlier instance is then passed into a new instance later on, a new "stale object" error is specially thrown when using this feature.

Building on this new Wasm Bindgen feature, layered with our new default panic handler, we also added a proxy wrapper to ensure all top-level exported class instantiations (such as for Rust Durable Objects) are tracked and fully reinitialized when resetting the Wasm instance. This was necessary because the workerd runtime will instantiate exported classes, which would then be associated with the Wasm instance.

This approach now provides full panic recovery for Rust Workers on subsequent requests.

Of course, we never want panics, but when they do happen they are isolated and can be investigated further from the error logs - avoiding broader service disruption.

In the future, full support for recoverable panics could be implemented without needing reinitialization at all, utilizing the WebAssembly Exception Handling ↗ proposal, part of the newly announced WebAssembly 3.0 ↗ specification. This would allow unwinding panics as normal JS errors, and concurrent requests would no longer fail.

We're making significant improvements to the reliability of Rust Workers ↗. Join us in #rust-on-workers on the Cloudflare Developers Discord ↗ to stay updated.

We recently increased the available disk space from 8 GB to 20 GB for all plans. Building on that improvement, we’re now doubling the CPU power available for paid plans — from 2 vCPU to 4 vCPU.

These changes continue our focus on making Workers Builds faster and more reliable.

• Fast build times: Even single-threaded workloads benefit from having more vCPUs
• 2x faster multi-threaded builds: Tools like esbuild ↗ and webpack ↗ can now utilize additional cores, delivering near-linear performance scaling

All other build limits — including memory, build minutes, and timeout remain unchanged.

To prevent the accidental exposure of applications, we've updated how Worker preview URLs (<PREVIEW>-<WORKER_NAME>.<SUBDOMAIN>.workers.dev) are handled. We made this change to ensure preview URLs are only active when intentionally configured, improving the default security posture of your Workers.

We performed a one-time update to disable preview URLs for existing Workers where the workers.dev subdomain was also disabled.

Because preview URLs were historically enabled by default, users who had intentionally disabled their workers.dev route may not have realized their Worker was still accessible at a separate preview URL. This update was performed to ensure that using a preview URL is always an intentional, opt-in choice.

If your Worker was affected, its preview URL (<PREVIEW>-<WORKER_NAME>.<SUBDOMAIN>.workers.dev) will now direct to an informational page explaining this change.

How to Re-enable Your Preview URL

If your preview URL was disabled, you can re-enable it via the Cloudflare dashboard by navigating to your Worker's Settings page and toggling on the Preview URL.

Alternatively, you can use Wrangler by adding the preview_urls = true setting to your Wrangler file and redeploying the Worker.

{
  "preview_urls": true
}

preview_urls = true

Note: You can set preview_urls = true with any Wrangler version that supports the preview URL flag (v3.91.0+). However, we recommend updating to v4.34.0 or newer, as this version defaults preview_urls to false, ensuring preview URLs are always enabled by explicit choice.