🌐 HTTP Header Analyzer

Analyzing your HTTP request headers...

✏️

Parse Custom Headers

Paste HTTP headers below to analyze them. The field is pre-populated with your current request headers.

⚠️ {{ customError }}
⚠️ {{ error }}

ℹ️ About HTTP Request Headers

HTTP request headers are field names and values sent by your browser whenever it loads a page, calls an API, follows a redirect, or submits a form. They reveal content preferences, protocol details, cookies, authentication hints, proxy forwarding data, and browser metadata that web servers use for routing, negotiation, caching, and security decisions.

Modern HTTP field semantics are defined by RFC 9110. HTTP/1.1 message handling is in RFC 9112, HTTP/2 in RFC 9113, and HTTP/3 in RFC 9114.

Common use cases:

  • Debug API calls, redirects, caches, language negotiation, and browser content preferences.
  • Compare headers before and after a CDN, reverse proxy, load balancer, or WAF change.
  • Inspect User-Agent, Accept, Accept-Language, and compression behavior for compatibility testing.
  • Check proxy identity headers such as Forwarded, X-Forwarded-For, and X-Real-IP.
  • Confirm whether cookies, authorization fields, or custom headers are present when troubleshooting authentication.

Headers worth reviewing:

  • Host: target authority for the request, required for HTTP/1.1 virtual hosting.
  • User-Agent: client software string; useful for diagnostics but unreliable as a security signal.
  • Accept / Accept-Language / Accept-Encoding: content, language, and compression preferences.
  • Origin: the origin of a browser fetch, important for CORS checks and defined alongside web origin behavior in RFC 6454.
  • Cookie: state sent back to the server; cookie behavior is specified by RFC 6265.
  • Authorization: bearer tokens, Basic credentials, or other authentication material.
  • Forwarded: standardized proxy forwarding header from RFC 7239.
  • Cache-Control / If-None-Match / If-Modified-Since: cache directives and conditional request fields.

Privacy and Trust Limits

  • This page shows the headers received by Online Cyber Tools plus any pasted custom headers you analyze.
  • Do not paste live session cookies, bearer tokens, API keys, or customer identifiers into shared debugging notes.
  • Forwarding headers are trustworthy only when added by infrastructure you control; arbitrary clients can spoof many X-* fields.
  • Some browser-controlled headers cannot be manually set by JavaScript, so pasted examples may differ from real browser traffic.

API Usage Example:

GET /api/tools/network/request-headers

curl "https://onlinecybertools.com/api/tools/network/request-headers"
Ready