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NeatUtility

HTTP Header Parser

Web & APIMemory Only100% Client-Side
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About this tool, examples & FAQ

Parse and inspect raw HTTP request and response headers with zero server calls. Categorize security headers, caching policies, and CORS directives, normalize casing, and export clean JSON structures locally in your browser.

Key facts

Verified capabilities and limits of this utility
HTTP SpecificationsRFC 9110 (HTTP Semantics), RFC 7230 (Message Syntax & Routing), RFC 6797 (HSTS)
Analyzed CategoriesSecurity, Caching, CORS, Content, Authentication, and Connection
Maximum Input50 KB
Execution Deadline2 s

How to use

  1. Paste raw HTTP headers copied from browser DevTools, curl `-i`, or server access logs.
  2. Select your desired view: Header Analysis with descriptions, Structured JSON, or Canonical Raw Headers.
  3. Optionally enable alphabetical sorting or disable sensitive token masking in the options drawer.
  4. Click Run (or press Ctrl/Cmd + Enter) to immediately analyze header definitions.
  5. Copy or export the normalized headers or JSON object into your codebase.

Example

Analyze standard HTTP response headers with status line

Input

HTTP/1.1 200 OK
content-type: application/json; charset=utf-8
cache-control: public, max-age=3600
strict-transport-security: max-age=31536000; includeSubDomains

Example output

Start Line: HTTP/1.1 200 OK
---
Total Headers: 3

Content-Type: application/json; charset=utf-8
  Category:    Content
  Explanation: MIME type and character encoding of the payload body.

Cache-Control: public, max-age=3600
  Category:    Caching
  Explanation: Directives for caching mechanisms in both browsers and shared proxies.

Strict-Transport-Security: max-age=31536000; includeSubDomains
  Category:    Security
  Explanation: HSTS header enforcing secure HTTPS connections and preventing downgrade attacks.

Edge cases

Obsolete Line Folding (RFC 7230)

Historic RFC 7230 header values split across multiple indented lines (continuation lines starting with spaces or tabs) are smoothly concatenated into single unified header values.

HTTP/2 and HTTP/3 Lowercase Normalization

Modern binary protocols like HTTP/2 and HTTP/3 require all header names to be sent in lowercase. The parser automatically restores standard canonical title-casing (e.g., 'etag' to 'ETag').

Sensitive Token Redaction

Credentials, Bearer tokens, API keys, and session cookies (`Authorization`, `Cookie`, `Set-Cookie`) are masked with `[REDACTED]` by default to prevent accidental credential leakage.

How it works

  1. Detects HTTP request methods or status codes on the initial line if present.
  2. Tokenizes header fields using colon delimiters and collapses multiline folding.
  3. Maps field names to canonical RFC title casing and classifies headers into functional categories.
  4. Performs all parsing entirely within client Web Worker memory with no outbound requests.

Related workflows

Frequently asked questions

Are pasted HTTP headers sent to any remote server?

No. All parsing, categorization, and redaction execute 100% locally inside your web browser. Nothing is transmitted over the network.

Why are HTTP/2 and HTTP/3 headers always lowercase?

The RFC 7540 specification mandates that all HTTP/2 and HTTP/3 header field names must be lowercase to optimize HPACK and QPACK header compression.

What are the most important HTTP security headers?

Recommended modern security headers include Strict-Transport-Security (HSTS), Content-Security-Policy (CSP), X-Content-Type-Options: nosniff, and Referrer-Policy.

References