HTTP Header Parser
Parse HTTP headers for inspection.
Parse HTTP headers for inspection.
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Tool guide
Free HTTP Header Parser
Parse pasted HTTP request or response header lines into structured JSON names and values. The offline parser preserves header-name casing, identifies repeated names case-insensitively, and reports malformed lines without contacting a website or server.
Steps
How it works
- Paste raw header lines in name: value format.
- Run the HTTP header parser in your browser.
- Review each name, value, and duplicate indicator.
- Copy the structured JSON or download it.
Highlights
Key features
- Parses both request and response header fields written as name-value lines.
- Splits each line at its first colon so later colons remain in the value.
- Preserves the entered header name and value text after surrounding whitespace is trimmed.
- Flags all occurrences of a repeated header name using case-insensitive matching.
- Rejects nonempty lines without a valid name followed by a colon.
Use cases
Common uses
- Turn copied request headers into structured JSON.
- Inspect repeated response header fields.
- Review header names and values from logs or documentation.
- Prepare header fixture data for tests and debugging.
Notes
Limitations to know
- The input must contain header fields only; request/status lines and folded continuation lines are not supported.
- Duplicate fields remain separate and comma-separated values are not split.
- Header names are not normalized to lowercase in the output.
- The parser is not an RFC-complete validator and does not interpret dates, cookies, authorization values, or security policies.
- It does not send HTTP requests, inspect a live server, test CORS, or grade security headers.
FAQ
Frequently asked questions
Can it parse request and response headers?
Yes. Either can be parsed when supplied as header-name and value lines. Request and status lines themselves are not supported.
Are duplicate headers preserved?
Yes. Every line remains in the result, and repeated names receive a duplicate flag.
Does it normalize header names?
No. Entered casing is preserved, although duplicate detection compares names case-insensitively.
What happens with malformed header lines?
A nonempty line without a name and colon causes a friendly validation error.
Does HTTP Header Parser test live websites or security headers?
No. It parses pasted text only and makes no network request or security assessment.