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Learn why the browser sends an OPTIONS preflight request before your API call, what triggers it, and how to fix CORS preflight errors on your server or with a proxy.

Fix the 'Response to preflight request doesn't pass access control check' CORS error. Learn why preflight OPTIONS requests fail and how to configure the correct CORS headers.

Enable Access-Control-Allow-Origin for multiple domains instantly. Learn why the header only accepts one value and how to dynamically set it server-side.

Learn how the Access-Control-Allow-Origin header works, how browsers enforce it step by step, common pitfalls, and what to do when you don't control the server.

Change Sec-Fetch-Mode and other Sec-Fetch headers in JavaScript. Learn why browsers block them and how to set them using a server-side proxy.

Fix the 'Refused to get unsafe header' error in JavaScript by adding Access-Control-Expose-Headers on your server, or using a CORS proxy like Corsfix when you don't control the API.

Fix the 'Refused to set unsafe header' error in JavaScript. Learn why browsers block certain request headers, which headers are forbidden, and how to bypass the restriction using a server-side proxy.

Set a custom User-Agent header in JavaScript fetch using a CORS proxy. Learn why browsers block it, common User-Agent strings, and how to override it for scraping and API access.

Send a custom Cookie header in JavaScript fetch using a CORS proxy. Learn why browsers block it, how to override it with a proxy, and how to handle Set-Cookie responses.

Set the Host header in JavaScript fetch using a CORS proxy. Learn why browsers block it, how to bypass the restriction, and best practices.

You can now set a custom cache duration for your CORS proxy responses in Corsfix, giving you more control over how long cached data is stored.

Learn how to hide API keys in your frontend code using a backend proxy. Understand why hiding keys client-side isn't possible and how Corsfix can help.

Get started with Corsfix to solve CORS errors on your website. Learn how to make your first request and integrate it into your website.

Learn how we serve multiple Astro projects under one domain using pnpm workspace, git submodules, and a custom build script.

Solve access blocked by CORS policy when fetching APIs. Learn how to fix the 'No Access-Control-Allow-Origin header' errors and why it occurs.

Corsfix Lite Plan is back with unlimited proxy requests and data transfer. Get started immediately without worrying about usage limits.

Learn why APIs don't enable CORS and how to ethically access these APIs from client-side applications.

Learn how to build a website screenshot tool without any backend infrasturcture or browser instances.

Fix the Content-Security-Policy in Neocities instantly. Learn why CSP errors happen and get detailed solution.

Fix CORS error in Gatsby, solve No Access‑Control‑Allow‑Origin instantly. Learn why CORS error happens.

Fix the No Access‑Control‑Allow‑Origin in Svelte instantly. Learn why CORS errors happen and compare all solutions.

Fix CORS error in Vue.js, solve No Access‑Control‑Allow‑Origin instantly. Learn why CORS error happens.

Fix CORS error in Angular, solve No Access‑Control‑Allow‑Origin instantly. Learn why CORS error happens.

Fix CORS error in Astro, solve No Access‑Control‑Allow‑Origin instantly. Learn why CORS error happens.

Fix CORS error in Flutter Web, solve No Access‑Control‑Allow‑Origin instantly. Learn why CORS error happens.

Fix the No Access‑Control‑Allow‑Origin in React instantly. Learn why CORS errors happen and compare all solutions.

This guide includes open source CORS proxy services you can self-host.

An analysis of CORS proxy security concerns and best practices for safe usage. Learn how to choose a secure CORS proxy service.

Find out why APIs use less bandwidth than websites. Learn how to plan bandwidth requirements for API services.

Corsfix is now open source! Learn about our commitment to transparency, privacy, and community-driven development.

Understand the role of a CORS proxy in bypassing CORS errors. See how it works, when to use it, and examples of implementation.

An all-in-one resource explaining CORS headers with practical examples, common errors, and solutions.

Find which HTTP headers browsers are safelisted for cross-origin requests and responses. Avoid unnecessary preflight checks and access response headers by default.

Learn how to enable CORS in Flask by manually setting headers per endpoint or using the flask-cors library for global and fine-grained control.

Fix GitHub release CORS error, fetch from the browser in minutes: step-by-step guide, backend relay or one-line proxy.

Fix tainted canvas errors easily. Set server headers or use a proxy. Learn how to work with cross-origin images in canvas.

Solve CORS error while fetching an external API. Learn how to bypass CORS restrictions using a backend relay or a CORS proxy.

Understand why 'No Access-Control-Allow-Origin' error happens and how to fix it with CORS headers or a CORS proxy.

Discover why `mode: 'no-cors'` fails to disable CORS and learn the proper approach to handle cross-origin requests.

Fix Figma plugin CORS error when making API calls. Learn how to bypass null origin issues using a non-null origin iframe.

Calling Swiggy API without CORS issues. Learn how to use a CORS proxy to fetch data from Swiggy's API in your frontend applications.

Our new online CORS Tester tool helps you quickly check if any URL supports CORS. Test API CORS support, customize requests, and simulate preflight requests.

These 7 key CORS terms will help you understand and troubleshoot CORS issues in your web applications. From Same Origin Policy to CORS proxies, get the insights you need.

Learn about CORS, its purpose, and how to handle CORS errors in your web applications. Understand the importance of CORS in modern web development.

Find out why using "no-cors" won't fix your CORS error. Learn why it leads to opaque responses and how to properly handle CORS issues.

Discover 10 essential tools and resources to master CORS. Learn how to troubleshoot errors, enable CORS across various frameworks, and streamline your development workflow.

Compare free CORS Anywhere with premium CORS proxy Corsfix. Learn the pros and cons of each, and find out which one is best for your needs.

Avoid common CORS mistakes, from forgetting the Access-Control-Allow-Origin header to using mode: no-cors. Learn how to fix them and improve your development process.