Understanding the HTTP OPTIONS Method

So far, we've explored concepts such as Origin, CORS, and Fetch Credentials.

In the next article, we'll discuss Preflight Requests, but before that, it's important to understand the HTTP OPTIONS method, since browsers rely on it during the preflight process.

What is the OPTIONS Method?

OPTIONS is one of the standard HTTP request methods.

Unlike methods such as GET or POST, which retrieve or modify resources, the OPTIONS method is used to discover the communication capabilities of a server for a particular resource.

In simple terms, the client is asking:

"If I want to interact with this resource, what operations do you support?"

The server typically does not perform any business logic or modify data. Instead, it simply returns information about the resource's supported capabilities.

How is OPTIONS Different from Other HTTP Methods?

Common HTTP methods are designed to perform specific actions:

• GET — Retrieve data
• POST — Create a resource
• PUT — Replace a resource
• PATCH — Partially update a resource
• DELETE — Remove a resource

The OPTIONS method is different.

Its purpose is not to manipulate resources but to describe what the server is willing to accept for a given endpoint.

For this reason, OPTIONS is generally considered an informational request.

Example Response

Suppose a client sends:

OPTIONS /users HTTP/1.1
Host: api.example.com

The server may respond with:

HTTP/1.1 204 No Content
Allow: GET, POST, PUT, DELETE, OPTIONS

The Allow header lists the HTTP methods supported by the resource.

In many modern APIs, an OPTIONS response may also include additional headers that are especially important for CORS, which we'll cover in the next article.

Do Developers Usually Send OPTIONS Requests?

In most applications, developers rarely send OPTIONS requests manually.

Instead, browsers automatically generate them in specific situations before sending the actual request.

The browser does this to verify whether the upcoming request is permitted.

This automatic verification process is known as a Preflight Request.

Why Should You Understand OPTIONS?

Many developers are surprised when they notice an OPTIONS request in the browser's Network tab and assume their application generated it.

In reality, it's usually the browser performing a protocol-level check before sending the actual request.

Understanding the purpose of the OPTIONS method makes it much easier to understand how CORS Preflight Requests work.