HTTP Header Builder

1. Select the header type. Choose request mode for client headers or response mode for server headers.
2. Set content negotiation. Configure Accept and Content-Type values that match the data format.
3. Add authentication carefully. Choose Bearer or Basic only when needed and avoid exposing real secrets.
4. Choose caching and CORS rules. Use restrictive defaults unless your application requires public caching or cross-origin access.
5. Add custom headers. Enter one Header-Name: value pair per line.
6. Generate and test. Copy the output into the target environment and confirm actual behavior with browser or API diagnostics.

How HTTP Header Builder works online

The HTTP Header Builder assembles a set of unique header names and values. Header names are checked against the token characters allowed by HTTP syntax. Values containing carriage returns or line feeds are rejected to reduce accidental header injection. Custom rows must contain a colon separating the name from the value.

HTTP field names are case-insensitive. For that reason, Content-Type and content-type refer to the same header. The builder replaces earlier duplicates and emits one final value per name.

HTTP Header Builder for Accept and Content-Type

Accept describes response formats the client prefers. Content-Type describes the actual format of the current message body. A JSON request commonly sends both Accept: application/json and Content-Type: application/json; charset=utf-8. A GET request without a body may not need Content-Type.

Common media types

Typical values include application/json, application/xml, text/plain, text/html, multipart/form-data, and application/x-www-form-urlencoded. The exact value must match the body and server expectations.

HTTP Header Builder authorization headers

Bearer authentication normally carries an access token. Basic authentication carries a Base64 representation of username and password. Both should be transmitted only over HTTPS and protected from logs, analytics, screenshots, and browser history. Many APIs also use custom headers such as X-API-Key; these can be added in the custom header field.

HTTP Header Builder for Cache-Control and CORS

Cache-Control: no-store is a restrictive option for sensitive data. no-cache allows storage but requires revalidation. Public max-age rules are suitable only when shared caches may safely reuse the response.

Access-Control-Allow-Origin is a response header. It does not grant access by itself when placed in a browser request. Configure CORS on the server and avoid combining wildcard origins with credentialed cross-origin requests.

HTTP Header Builder response security headers

The optional security preset adds practical baseline headers, but it is not a complete security configuration. Production websites should also evaluate Content-Security-Policy, Strict-Transport-Security, Permissions-Policy, cookie attributes, CSRF defenses, and framework-specific protections.

12 powerful HTTP Header Builder examples

JSON API request

Accept: application/json
Authorization: Bearer demo-token
Content-Type: application/json; charset=utf-8

Private API response

Cache-Control: no-store
Content-Type: application/json; charset=utf-8
Referrer-Policy: strict-origin-when-cross-origin
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN

CORS-enabled response

Access-Control-Allow-Origin: https://app.example.com
Content-Type: application/json; charset=utf-8

Common HTTP Header Builder mistakes

Using response headers in requests

Headers such as Access-Control-Allow-Origin are generated by the server. Adding them to a browser request does not bypass CORS enforcement.

Publishing secrets

Authorization values, API keys, cookies, and session identifiers should be treated as credentials. Replace real values with placeholders in documentation and screenshots.

Confusing Accept and Content-Type

Accept describes preferred response media types. Content-Type describes the body being sent or returned.

Unsafe public caching

Do not use public cache directives for personalized, authenticated, or confidential responses unless the architecture explicitly supports it.

HTTP Header Builder related tools

Create a complete command with cURL Builder, review response meanings with HTTP Status Code Lookup, or inspect URL parameters with Query String Parser.

Authoritative references

Review the HTTP Semantics specification and the MDN HTTP headers reference before deploying security-sensitive rules.