Will it follow RFC 7230 capitalisation?

Yes. Header names are normalised to canonical capitalisation (each word starting uppercase). The HTTP spec treats names as case-insensitive but most tools display them this way.

Are the headers sent anywhere?

No. Processing is local in your browser. Headers containing authentication tokens or cookies stay on the device.

Does it parse the request line or status line?

Yes. The first line (e.g. GET /path HTTP/1.1 or HTTP/1.1 200 OK) is recognised and kept at the top.

Will it deduplicate headers?

No. Repeated headers like Set-Cookie or Via are kept as separate lines because their order is significant.

http · title-case · sort · live

Format HTTP headers for readability

Parses request or response headers, title-cases the names (Content-Type, X-Rate-Limit), sorts alphabetically, and aligns the colon. Runs locally.

HTTP Headers Formatter

Input

124 B

5 lines

Output

140 B

6 lines

Status

ready

live

Ratio

1.13×

out/in

input · raw headers

output · formatted headers

HTTP/1.1 200 OK

Cache-Control : no-store
Content-Type  : application/json
Date          : Wed, 01 Jan 2025 00:00:00 GMT
X-Rate-Limit  : 100

Quick Start

How to format HTTP headers

Detects request / response status lines, sorts the remaining headers, and aligns names in title case for quick scanning.

01
Paste raw headers
Curl -i output, devtools "copy as headers", server logs — they all work.
Parsing runs through Prettier’s standalone bundle (or the language-specific equivalent) loaded lazily — no parser ships until the tool is opened.
httpPrettierASTstandalonelazy
input · sourceraw · AST
```
content-type: text/html
```
loaded · parsedAST · ready
02
Title-case applied
Each header name is split on - and each part capitalised — RFC-friendly canonical form.
Indent width, tab style, and print-width re-format through a memoised pass — switching 2 → 4 spaces never re-parses, only re-prints.
caseindentprint-widthmemoisedlive
step · optionsname · live
```
Content-Type
```
options applied · livelive
03
Sorted & aligned
Headers are sorted alphabetically; the colon column lines up to the longest name.
The formatter is deterministic and idempotent: running it twice produces byte-identical output, which keeps diffs and git noise to a minimum.
liveidempotentdeterministicdiff-cleanstable
out · formattedaligned · ready
```
Content-Type : text/html
```
formatted · liveidempotent
04
Copy or download
Drop the cleaned-up headers into a doc, ticket, or runbook.
Download writes a Blob with the language-appropriate extension; copy uses navigator.clipboard.writeText so the output preserves all whitespace exactly.
exportclipboardbloblanguage MIMEclient-side
ok · copiedready · done
```
✓ Copied
```
shipped · ready to shipsuccess

Pro tips

Formatting tips that keep diffs sane

Pick one config and pin it

Inconsistent formatting causes diff churn. Commit .prettierrc / .editorconfig and enforce in CI.

Format on save

Editor integration is faster feedback than a pre-commit hook. Use both for belt-and-braces.

Idempotency matters

Running the formatter twice should produce identical output. Test this on a representative file.

Match the language community

Default to community conventions: 2 spaces for JS/CSS, 4 for Python, tabs for Go. Fights over indent are a productivity tax.

Print-width drives wrapping

80, 100, and 120 are the common targets. Wider lines parse fast but review slower side-by-side.

Don’t mix formatters and linters

Prettier handles whitespace; ESLint handles correctness. Disable overlapping rules to avoid fight-club configs.

Use Cases

When to format HTTP headers

API debug, security review, doc snippets.

API debug

Read a busy response header set at a glance. Idempotent: running the formatter twice produces byte-identical output, which is the foundation of a clean CI gate. Pair with a pre-commit hook so PRs arrive already formatted, focusing review on logic.

idempotent

Security review

Audit CSP, HSTS, and CORS headers side-by-side. Pairs with EditorConfig + .prettierrc for end-to-end consistency. Whitespace-only changes vanish so reviewers see real diffs, and git blame stays honest about who wrote what.

CI-ready

Doc snippets

Include canonicalised headers in runbooks. Output respects your indent width, tab style, and print-width — settings carry over for repeat runs. Switching 2-space to 4-space costs nothing in CPU but standardises an entire codebase.

diff-clean

Curl traces

Tidy `curl -i` output before sharing in a ticket. Format-on-save is the fastest feedback loop; CI is the safety net. Together they make inconsistent indentation a thing of the past and free up review cycles for genuine concerns.

PR-friendly

Cache audit

Compare Cache-Control / ETag values across endpoints. Whitespace-only changes don't trigger downstream content-hash invalidations, so CDN cache keys and CI cache layers stay warm. Real changes get all the rebuild budget.

review-ready

Vendor support

Send clean headers to a vendor for triage. Pairs with linters (ESLint, Stylelint, pylint) that catch what formatting alone can't — bugs, unused imports, dead code. Each tool stays in its lane, and the codebase stays clean.

deterministic

FAQ

Frequently asked questions

Are values modified?

No — only the header name is canonicalised; values are passed through verbatim.

What about request lines?

GET / POST / etc and HTTP/1.x status lines are detected and printed on top with a blank line below.

Does it parse multi-line headers?

Continuation lines (RFC 7230 obs-fold) are deprecated and not specially handled — keep headers on one line.

Cookies and Set-Cookie?

Each Set-Cookie header is treated as a separate line; values stay exactly as written.

Is anything sent to a server?

No — the formatter runs locally in your browser tab.

Suggest a tool

Something missing?

Tell us what you need. We ship the top requests every two weeks.

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