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HTTP Request Header Builder

DataDeveloperNetworking

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INPUT

Auto Process

OUTPUT

Client Side

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Guide

HTTP Request Header Builder

Build HTTP request headers visually. Add common headers from a dropdown (Authorization, Content-Type, Accept, Cache-Control, etc.), configure authentication (Bearer token, Basic auth, API key), and add custom headers. The output is a ready-to-copy header block formatted for curl, fetch, or any HTTP client.

How to Use

Use the Add Common Header dropdown to insert frequently used headers with sensible defaults. Set your auth type and credentials in the auth section, then add any custom headers manually. Copy the complete header set for use in curl, Postman, or your code.

Features

Common header presets – Content-Type, Accept, Authorization, Cache-Control, and more
Auth type selector – Bearer token, Basic auth, API key
Custom headers – add any header name/value pair
Multiple output formats – formatted for curl -H flags or JavaScript fetch
Real-time preview – see the full header block as you build
Client-side only – credentials never leave your browser

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 FAQ

What are the most important HTTP request headers to know?

Authorization: carries credentials (Bearer token, Basic, API key). Content-Type: tells the server the format of the request body (application/json, multipart/form-data). Accept: tells the server what response format the client expects. Cache-Control: controls caching behaviour. User-Agent: identifies the client application. Correlation-Id / X-Request-Id: for distributed tracing. CORS preflight headers (Origin, Access-Control-Request-Method) are added automatically by browsers.
What is the difference between Bearer token and Basic authentication?

Basic authentication sends credentials as Base64-encoded username:password in the Authorization header. It is simple but must always be used over HTTPS since Base64 is trivially decodable. Bearer token authentication sends an opaque token (typically a JWT) issued by an identity provider. Bearer tokens can be scoped, time-limited, and revoked independently. OAuth 2.0 and OpenID Connect use Bearer tokens as the standard for API authentication.
What does Content-Type: application/json vs multipart/form-data mean?

application/json indicates the request body is a JSON-encoded string and the server should parse it as JSON. multipart/form-data is used for file uploads or form submissions containing binary data, where the body is divided into named parts separated by a boundary string. application/x-www-form-urlencoded is used for simple HTML form submissions where data is URL-encoded as key=value pairs.
What are CORS preflight headers and why are they added automatically by browsers?

CORS (Cross-Origin Resource Sharing) is a browser security policy that restricts cross-origin requests. When a JavaScript application makes a cross-origin request with custom headers or non-simple methods, the browser automatically sends an OPTIONS preflight request with Origin and Access-Control-Request-Method/Headers. The server must respond with appropriate Access-Control-Allow-* headers for the browser to permit the actual request. Server-side applications and curl are not subject to CORS.