Accept

General Summary

Tells the server what format of data the client is expecting to receive.

Detailed Description

The Accept request HTTP header specifies the content types (expressed as MIME types) that a client can understand and prefers to receive in response to a request. This is a primary driver of a process called Content Negotiation, where the server uses the Accept header to decide which representation of the resource to send back when multiple are available (e.g., returning JSON instead of HTML).

Use Cases (When, Why, and How)

When to Use It

Client applications (like web browsers or API consumers) automatically send this header to ensure they receive data in a format they can parse.

Why to Use It

It decouples the client and server by allowing a single API endpoint to serve multiple formats depending on who is asking for it. This prevents the need for format-specific URLs like /data.json or /data.xml.

How to Use It

You provide a comma-separated list of MIME types. You can also append a relative quality factor (q=0.8 to q=1.0) to indicate a preference weighting for different types.

• Browsers: Automatically attach Accept: text/html,application/xhtml+xml... when navigating to pages.
• API Calls: When using fetch() or axios in Javascript, you often manually set Accept: application/json so the backend knows you want a JSON response instead of a rendered view.

Example

Accept: application/json, text/plain, */*