---
title: Examples
description: Browse code examples and starter templates for Cloudflare Workers.
image: https://developers.cloudflare.com/dev-products-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/workers/llms.txt  
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# Examples

Explore the following examples for Workers.

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[Single Page App (SPA) shell with bootstrap dataUse HTMLRewriter to inject prefetched bootstrap data into an SPA shell, eliminating client-side data fetching on initial load. Works with Workers Static Assets or an externally hosted SPA.](https://developers.cloudflare.com/workers/examples/spa-shell/)[Write to Analytics EngineWrite custom analytics events to Workers Analytics Engine for high-cardinality, time-series data.](https://developers.cloudflare.com/workers/examples/analytics-engine/)[Stream large JSONParse and transform large JSON request and response bodies using streaming.](https://developers.cloudflare.com/workers/examples/streaming-json/)[HTTP Basic AuthenticationShows how to restrict access using the HTTP Basic schema.](https://developers.cloudflare.com/workers/examples/basic-auth/)[Fetch HTMLSend a request to a remote server, read HTML from the response, and serve that HTML.](https://developers.cloudflare.com/workers/examples/fetch-html/)[Return small HTML pageDeliver an HTML page from an HTML string directly inside the Worker script.](https://developers.cloudflare.com/workers/examples/return-html/)[Return JSONReturn JSON directly from a Worker script, useful for building APIs and middleware.](https://developers.cloudflare.com/workers/examples/return-json/)[Sign requestsVerify a signed request using the HMAC and SHA-256 algorithms or return a 403.](https://developers.cloudflare.com/workers/examples/signing-requests/)[Stream OpenAI API ResponsesUse the OpenAI v4 SDK to stream responses from OpenAI.](https://developers.cloudflare.com/workers/examples/openai-sdk-streaming/)[Using timingSafeEqualProtect against timing attacks by safely comparing values using timingSafeEqual.](https://developers.cloudflare.com/workers/examples/protect-against-timing-attacks/)[Turnstile with WorkersInject Turnstile implicitly into HTML elements using the HTMLRewriter runtime API.](https://developers.cloudflare.com/workers/examples/turnstile-html-rewriter/)[Custom Domain with ImagesSet up custom domain for Images using a Worker or serve images using a prefix path and Cloudflare registered domain.](https://developers.cloudflare.com/workers/examples/images-workers/)[103 Early HintsAllow a client to request static assets while waiting for the HTML response.](https://developers.cloudflare.com/workers/examples/103-early-hints/)[Cache Tags using WorkersSend Additional Cache Tags using Workers](https://developers.cloudflare.com/workers/examples/cache-tags/)[Accessing the Cloudflare ObjectAccess custom Cloudflare properties and control how Cloudflare features are applied to every request.](https://developers.cloudflare.com/workers/examples/accessing-the-cloudflare-object/)[Aggregate requestsSend two GET request to two urls and aggregates the responses into one response.](https://developers.cloudflare.com/workers/examples/aggregate-requests/)[Block on TLSInspects the incoming request's TLS version and blocks if under TLSv1.2.](https://developers.cloudflare.com/workers/examples/block-on-tls/)[Bulk redirectsRedirect requests to certain URLs based on a mapped object to the request's URL.](https://developers.cloudflare.com/workers/examples/bulk-redirects/)[Cache POST requestsCache POST requests using the Cache API.](https://developers.cloudflare.com/workers/examples/cache-post-request/)[Conditional responseReturn a response based on the incoming request's URL, HTTP method, User Agent, IP address, ASN or device type.](https://developers.cloudflare.com/workers/examples/conditional-response/)[Cookie parsingGiven the cookie name, get the value of a cookie. You can also use cookies for A/B testing.](https://developers.cloudflare.com/workers/examples/extract-cookie-value/)[Fetch JSONSend a GET request and read in JSON from the response. Use to fetch external data.](https://developers.cloudflare.com/workers/examples/fetch-json/)[Geolocation: Custom StylingPersonalize website styling based on localized user time.](https://developers.cloudflare.com/workers/examples/geolocation-custom-styling/)[Geolocation: Hello WorldGet all geolocation data fields and display them in HTML.](https://developers.cloudflare.com/workers/examples/geolocation-hello-world/)[Post JSONSend a POST request with JSON data. Use to share data with external servers.](https://developers.cloudflare.com/workers/examples/post-json/)[RedirectRedirect requests from one URL to another or from one set of URLs to another set.](https://developers.cloudflare.com/workers/examples/redirect/)[Rewrite linksRewrite URL links in HTML using the HTMLRewriter. This is useful for JAMstack websites.](https://developers.cloudflare.com/workers/examples/rewrite-links/)[Set security headersSet common security headers (X-XSS-Protection, X-Frame-Options, X-Content-Type-Options, Permissions-Policy, Referrer-Policy, Strict-Transport-Security, Content-Security-Policy).](https://developers.cloudflare.com/workers/examples/security-headers/)[Multiple Cron TriggersSet multiple Cron Triggers on three different schedules.](https://developers.cloudflare.com/workers/examples/multiple-cron-triggers/)[Setting Cron TriggersSet a Cron Trigger for your Worker.](https://developers.cloudflare.com/workers/examples/cron-trigger/)[Using the WebSockets APIUse the WebSockets API to communicate in real time with your Cloudflare Workers.](https://developers.cloudflare.com/workers/examples/websockets/)[Geolocation: Weather applicationFetch weather data from an API using the user's geolocation data.](https://developers.cloudflare.com/workers/examples/geolocation-app-weather/)[A/B testing with same-URL direct accessSet 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.](https://developers.cloudflare.com/workers/examples/ab-testing/)[Alter headersExample of how to add, change, or delete headers sent in a request or returned in a response.](https://developers.cloudflare.com/workers/examples/alter-headers/)[Auth with headersAllow or deny a request based on a known pre-shared key in a header. This is not meant to replace the WebCrypto API.](https://developers.cloudflare.com/workers/examples/auth-with-headers/)[Bulk origin overrideResolve requests to your domain to a set of proxy third-party origin URLs.](https://developers.cloudflare.com/workers/examples/bulk-origin-proxy/)[Using the Cache APIUse the Cache API to store responses in Cloudflare's cache.](https://developers.cloudflare.com/workers/examples/cache-api/)[Cache using fetchDetermine how to cache a resource by setting TTLs, custom cache keys, and cache headers in a fetch request.](https://developers.cloudflare.com/workers/examples/cache-using-fetch/)[CORS header proxyAdd the necessary CORS headers to a third party API response.](https://developers.cloudflare.com/workers/examples/cors-header-proxy/)[Country code redirectRedirect a response based on the country code in the header of a visitor.](https://developers.cloudflare.com/workers/examples/country-code-redirect/)[Data loss preventionProtect sensitive data to prevent data loss, and send alerts to a webhooks server in the event of a data breach.](https://developers.cloudflare.com/workers/examples/data-loss-prevention/)[Debugging logsSend debugging information in an errored response to a logging service.](https://developers.cloudflare.com/workers/examples/debugging-logs/)[Hot-link protectionBlock other websites from linking to your content. This is useful for protecting images.](https://developers.cloudflare.com/workers/examples/hot-link-protection/)[Logging headers to consoleExamine the contents of a Headers object by logging to console with a Map.](https://developers.cloudflare.com/workers/examples/logging-headers/)[Modify request propertyCreate a modified request with edited properties based off of an incoming request.](https://developers.cloudflare.com/workers/examples/modify-request-property/)[Modify responseFetch and modify response properties which are immutable by creating a copy first.](https://developers.cloudflare.com/workers/examples/modify-response/)[Read POSTServe an HTML form, then read POST requests. Use also to read JSON or POST data from an incoming request.](https://developers.cloudflare.com/workers/examples/read-post/)[Respond with another siteRespond to the Worker request with the response from another website (example.com in this example).](https://developers.cloudflare.com/workers/examples/respond-with-another-site/)

```json
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/workers/","name":"Workers"}},{"@type":"ListItem","position":3,"item":{"@id":"/workers/examples/","name":"Examples"}}]}
```