HTTP Header Parser

About this tool

Response headers decide caching, security, CORS and content handling — but raw header blocks are dense reading. This parser splits a pasted request or response into a clean table and explains what ~40 common headers actually do, from Cache-Control to Strict-Transport-Security.

Status lines are decoded too, with the status code classified at a glance.

How to use it

1. Copy headers from DevTools (Network tab → Raw), curl -i output, or logs.
2. Paste them into the input.
3. Read the parsed table — name, value, and meaning for each header.
4. Malformed lines are flagged separately so you can spot typos.

Useful ways to apply it

• Debugging caching behavior via Cache-Control, ETag and Vary.
• Auditing security headers before a deployment.
• Understanding CORS responses during cross-origin debugging.
• Teaching juniors what each header in a response does.

Worked example

HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store

Status 200; Content-Type application/json; Cache-Control no-store

Edge cases to check

• Header names are case-insensitive.
• Repeated headers may be combined differently depending on the field.
• Set-Cookie must not be blindly comma-joined like ordinary list headers.

Known limitations

Parsing text is not the same as validating whether a live server or browser actually applies a header.