Using Requestly for HTTP authorization

Authentication is how websites and apps make sure you are who you say you are. It’s what allows users to log in, access their personal data, and use protected features like paid services etc.

In most web apps, Authorization happens through HTTP requests. These requests include headers—small pieces of information sent along with each request. One important job of headers is to carry authentication credentials, like tokens or API keys, so the server knows which user is making the request.

As a developer or tester, you might need to simulate different authentication scenarios:

• Pretend to be a logged-in or logged-out user
• Switch between different user roles (like admin vs regular user)
• Test how your app handles expired or invalid tokens

Instead of changing backend code or modifying frontend logic, you can use tools like Requestly to modify these headers on the fly—directly in your browser. But before we dive into how, let’s take a closer look at how headers are used in authentication.

These headers are usually added automatically once a user logs in, but during development or testing, it’s often useful to manually add or modify them. That’s exactly what you can do with Requestly—making it easy to test authentication behaviour without writing extra code.