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45 examples

  • Deliver an HTML page from an HTML string directly inside the Worker script.
  • Return JSON directly from a Worker script, useful for building APIs and middleware.
  • Send a request to a remote server, read HTML from the response, and serve that HTML.
  • Send a GET request and read in JSON from the response. Use to fetch external data.
  • Redirect requests from one URL to another or from one set of URLs to another set.
  • Access custom Cloudflare properties and control how Cloudflare features are applied to every request.
  • Respond to the Worker request with the response from another website ( in this example).
  • Allow a client to request static assets while waiting for the HTML response.
  • Set up an A/B test by controlling what response is served based on cookies. This version supports passing the request through to test and control on the origin, bypassing random assignment.
  • Send two GET request to two urls and aggregates the responses into one response.
  • Example of how to add, change, or delete headers sent in a request or returned in a response.
  • Allow or deny a request based on a known pre-shared key in a header. This is not meant to replace the WebCrypto API.
  • Inspects the incoming request’s TLS version and blocks if under TLSv1.2.
  • Resolve requests to your domain to a set of proxy third-party origin URLs.
  • Redirect requests to certain URLs based on a mapped object to the request’s URL.
  • Cache POST requests using the Cache API.
  • Send Additional Cache Tags using Workers
  • Determine how to cache a resource by setting TTLs, custom cache keys, and cache headers in a fetch request.
  • Return a response based on the incoming request’s URL, HTTP method, User Agent, IP address, ASN or device type.
  • Given the cookie name, get the value of a cookie. You can also use cookies for A/B testing.
  • Add the necessary CORS headers to a third party API response.
  • Redirect a response based on the country code in the header of a visitor.
  • Set up custom domain for Images using a Worker or serve images using a prefix path and Cloudflare registered domain.
  • Protect sensitive data to prevent data loss, and send alerts to a webhooks server in the event of a data breach.
  • Send debugging information in an errored response to a logging service.
  • Personalize website styling based on localized user time.
  • Get all geolocation data fields and display them in HTML.
  • Fetch weather data from an API using the user’s geolocation data.
  • Block other websites from linking to your content. This is useful for protecting images.
  • Shows how to restrict access using the HTTP Basic schema.
  • Examine the contents of a Headers object by logging to console with a Map.
  • Create a modified request with edited properties based off of an incoming request.
  • Fetch and modify response properties which are immutable by creating a copy first.
  • Set multiple Cron Triggers on three different schedules.
  • Send a POST request with JSON data. Use to share data with external servers.
  • Serve an HTML form, then read POST requests. Use also to read JSON or POST data from an incoming request.
  • Rewrite URL links in HTML using the HTMLRewriter. This is useful for JAMstack websites.
  • Set common security headers (X-XSS-Protection, X-Frame-Options, X-Content-Type-Options, Permissions-Policy, Referrer-Policy, Strict-Transport-Security, Content-Security-Policy).
  • Set a Cron Trigger for your Worker.
  • Verify a signed request using the HMAC and SHA-256 algorithms or return a 403.
  • Use the OpenAI v4 SDK to stream responses from OpenAI.
  • Inject Turnstile implicitly into HTML elements using the HTMLRewriter runtime API.
  • Use the Cache API to store responses in Cloudflare’s cache.
  • Protect against timing attacks by safely comparing values using timingSafeEqual.
  • Use the WebSockets API to communicate in real time with your Cloudflare Workers.