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