Advanced Header and Cookie Management

1. HTTP Headers

What are HTTP Headers?

HTTP headers are key-value pairs sent in HTTP requests and responses. They provide essential information about the request or response, such as content type, encoding, caching policies, and more.

Types of HTTP Headers

General Headers
Request Headers
Response Headers
Entity Headers

Note: Headers are case-insensitive. For example, "Content-Type" and "content-type" are equivalent.

Common HTTP Headers

Content-Type: Specifies the media type of the resource.
Authorization: Contains credentials for authenticating a user.
User-Agent: Provides information about the client application.
Set-Cookie: Used to send cookies from the server to the client.

Example of HTTP Headers in a Request

GET / HTTP/1.1
Host: www.example.com
User-Agent: Mozilla/5.0
Accept: text/html
Content-Type: application/json

2. Cookie Management

What are Cookies?

Cookies are small pieces of data stored on the client-side to manage stateful information for web sessions. They are typically used for session management, personalization, and tracking user behavior.

Setting Cookies

Using Set-Cookie Header

The server can set cookies using the Set-Cookie header:

HTTP/1.1 200 OK
Set-Cookie: sessionId=abc123; HttpOnly; Secure; SameSite=Strict

Cookies Attributes

HttpOnly: Prevents JavaScript from accessing the cookie.
Secure: The cookie is sent only over HTTPS.
SameSite: Controls whether cookies are sent with cross-site requests.

Tip: Use Secure and HttpOnly flags for sensitive cookies to enhance security.

Reading Cookies

Cookies can be accessed in the browser using JavaScript:

const cookies = document.cookie;
console.log(cookies); // Outputs all cookies in a string format

3. Best Practices

Always use secure attributes for sensitive cookies.
Limit the scope of cookies by specifying the Domain and Path attributes.
Keep cookie size under 4KB to avoid issues with storage limits.
Regularly review and update your cookie policies to comply with privacy regulations.

4. FAQ

What is the maximum size of a cookie?

The maximum size of a cookie is generally 4KB (4096 bytes).

How many cookies can a website store?

Most browsers allow a maximum of 20 cookies per domain and a total of 300 cookies across all domains.

Are cookies secure?

Cookies can be secure if proper attributes (like Secure and HttpOnly) are set. However, they can still be vulnerable to attacks like XSS and CSRF.