HTTP Field Name Registry API

Q: Are HTTP field-name lookups case-sensitive?

No. /lookup?name=content-type resolves the registered Content-Type row because HTTP field names are case-insensitive.

Q: What does structuredType mean?

It is IANA's optional RFC 9651 classification: Dictionary, List, Item or Token. A null value means the registry has not assigned a Structured Field type.

Q: How is the registry snapshot refreshed?

scripts/refresh-http-fields.mjs fetches the official CSV and XML metadata, validates the complete source and regenerates the typed file with its update date and SHA-256.

REAL DATA

Complete pinned IANA HTTP field-name registry with status, Structured Field type, references, search and case-insensitive lookup.

Authoritative reference data or standards computation

Base URL: /api/http-fields
Category: Developer Tools
Capabilities: 2 routes
Last updated: July 29, 2026

Data source: IANA Hypertext Transfer Protocol Field Name Registry (updated 2026-07-01)

GET /api/http-fields List and filter every registered HTTP field name Returns a list

Live requestRuns against the public API

No key required

GET/api/http-fields?status=deprecated

Request parameters

statusdefault any

Filter by normalized IANA registration status; returned spelling stays source-exact.

structuredTypedefault any

Filter by RFC 9651 Structured Field type, or 'none' for rows without one.

search

Case-insensitive substring search across name, reference and comments.

Advanced response options6 options

countdefault all matches

Limit the number of returned records (1–100). Defaults to all matches.

fields

Return only these fields (comma-separated). Mutually exclusive with 'exclude'.

exclude

Return all fields except these (comma-separated).

formatdefault json

Response format: json envelope, ndjson (one record per line) or csv.

prettydefault false

Pretty-print the JSON response.

unwrapdefault false

Drop the envelope: return the raw array/object without data/meta wrapper.

Response

Example parameters are ready. Send the request to inspect the live response.

Route reference

Code, request parameters, response fields and verified examples 9 params · 5 fields · 3 examples

Code samples Ready-to-copy requests in 4 languages

curl JavaScript Python PHP

curl "https://randomapi.dev/api/http-fields?status=deprecated"

const res = await fetch("https://randomapi.dev/api/http-fields?status=deprecated");
const { data, meta } = await res.json();

import requests

data = requests.get("https://randomapi.dev/api/http-fields?status=deprecated").json()["data"]

$json = json_decode(file_get_contents(
  "https://randomapi.dev/api/http-fields?status=deprecated"
), true);
$data = $json["data"];

Parameters Route-specific request inputs 3

Parameter	Type	Default & allowed	Description
`status`	enum	default: any allowed: any \| permanent \| provisional \| deprecated \| obsoleted example: deprecated	Filter by normalized IANA registration status; returned spelling stays source-exact.
`structuredType`	enum	default: any allowed: any \| dictionary \| list \| item \| token \| none example: dictionary	Filter by RFC 9651 Structured Field type, or 'none' for rows without one.
`search`	string	allowed: 1 – 128 example: digest	Case-insensitive substring search across name, reference and comments.

status enum

Filter by normalized IANA registration status; returned spelling stays source-exact.

default: any

allowed: any | permanent | provisional | deprecated | obsoleted

example: status=deprecated

structuredType enum

Filter by RFC 9651 Structured Field type, or 'none' for rows without one.

default: any

example: structuredType=dictionary

search string

Case-insensitive substring search across name, reference and comments.

allowed: 1 – 128

example: search=digest

Universal parameters Shared response and formatting options 6

Parameter	Type	Default & allowed	Description
`count`	int	default: all matches allowed: 1 – 100 example: 3	Limit the number of returned records (1–100). Defaults to all matches.
`fields`	list	example: name,status	Return only these fields (comma-separated). Mutually exclusive with 'exclude'.
`exclude`	list	example: comments	Return all fields except these (comma-separated).
`format`	enum	default: json allowed: json \| ndjson \| csv example: csv	Response format: json envelope, ndjson (one record per line) or csv.
`pretty`	boolean	default: false example: true	Pretty-print the JSON response.
`unwrap`	boolean	default: false example: true	Drop the envelope: return the raw array/object without data/meta wrapper.

count int

Limit the number of returned records (1–100). Defaults to all matches.

default: all matches

allowed: 1 – 100

example: count=3

fields list

Return only these fields (comma-separated). Mutually exclusive with 'exclude'.

example: fields=name,status

exclude list

Return all fields except these (comma-separated).

example: exclude=comments

format enum

Response format: json envelope, ndjson (one record per line) or csv.

default: json

allowed: json | ndjson | csv

example: format=csv

pretty boolean

Pretty-print the JSON response.

default: false

example: pretty=true

unwrap boolean

Drop the envelope: return the raw array/object without data/meta wrapper.

default: false

example: unwrap=true

Response schema Fields returned in each record 5

Field	Type	Description	Example
`name`	string	HTTP field name exactly as registered by IANA.	Accept
`status`	string	IANA registration status, preserving the source CSV's spelling.	permanent
`structuredType` nullable	string	RFC 9651 Structured Field type (Dictionary, List, Item or Token), or null when unregistered.	List
`reference`	string	Specification reference copied from the pinned IANA registry row.	[RFC 9110, Section 12.5.1: HTTP Semantics]
`comments` nullable	string	IANA registry comment, or null when the row has no comment.	(reserved)

name string

HTTP field name exactly as registered by IANA.

example: Accept

status string

IANA registration status, preserving the source CSV's spelling.

example: permanent

structuredType string nullable

RFC 9651 Structured Field type (Dictionary, List, Item or Token), or null when unregistered.

example: List

reference string

Specification reference copied from the pinned IANA registry row.

example: [RFC 9110, Section 12.5.1: HTTP Semantics]

comments string nullable

IANA registry comment, or null when the row has no comment.

example: (reserved)

Documented examples

Build-generated requests and complete responses 3

Deprecated HTTP fields /api/http-fields?status=deprecated

GET /api/http-fields?status=deprecated

{
  "data": [
    {
      "name": "Accept-Charset",
      "status": "deprecated",
      "structuredType": null,
      "reference": "[RFC 9110, Section 12.5.2: HTTP Semantics]",
      "comments": null
    },
    {
      "name": "C-PEP-Info",
      "status": "deprecated",
      "structuredType": null,
      "reference": "[PEP - an Extension Mechanism for HTTP]",
      "comments": "[Status change of HTTP experiments to Historic]"
    },
    {
      "name": "Content-ID",
      "status": "deprecated",
      "structuredType": null,
      "reference": "[The HTTP Distribution and Replication Protocol]",
      "comments": null
    },
    {
      "name": "Differential-ID",
      "status": "deprecated",
      "structuredType": null,
      "reference": "[The HTTP Distribution and Replication Protocol]",
      "comments": null
    },
    {
      "name": "Expect-CT",
      "status": "deprecated",
      "structuredType": null,
      "reference": "[RFC 9163: Expect-CT Extension for HTTP]",
      "comments": "Obsoleted by [IESG]\n        [HTTPBIS]"
    },
    {
      "name": "Pragma",
      "status": "deprecated",
    …
    "generatedAt": "2026-07-29T08:13:22.000Z"
  }
}

Structured dictionaries /api/http-fields?structuredType=dictionary

GET /api/http-fields?structuredType=dictionary

{
  "data": [
    {
      "name": "CDN-Cache-Control",
      "status": "permanent",
      "structuredType": "Dictionary",
      "reference": "[RFC 9213: Targeted HTTP Cache Control]",
      "comments": "Cache directives targeted at content delivery networks"
    },
    {
      "name": "Content-Digest",
      "status": "permanent",
      "structuredType": "Dictionary",
      "reference": "[RFC 9530, Section 2: Digest Fields]",
      "comments": null
    },
    {
      "name": "Priority",
      "status": "permanent",
      "structuredType": "Dictionary",
      "reference": "[RFC 9218: Extensible Prioritization Scheme for HTTP]",
      "comments": null
    },
    {
      "name": "Repr-Digest",
      "status": "permanent",
      "structuredType": "Dictionary",
      "reference": "[RFC 9530, Section 3: Digest Fields]",
      "comments": null
    },
    {
      "name": "Signature",
      "status": "permanent",
      "structuredType": "Dictionary",
      "reference": "[RFC 9421, Section 4.2: HTTP Message Signatures]",
      "comments": null
    },
    {
      "name": "Signature-Input",
      "status": "permanent",
    …
    "generatedAt": "2026-07-29T08:13:22.000Z"
  }
}

Search digest-related registrations /api/http-fields?search=digest&count=20

GET /api/http-fields?search=digest&count=20

{
  "data": [
    {
      "name": "Content-Digest",
      "status": "permanent",
      "structuredType": "Dictionary",
      "reference": "[RFC 9530, Section 2: Digest Fields]",
      "comments": null
    },
    {
      "name": "Digest",
      "status": "obsoleted",
      "structuredType": null,
      "reference": "[RFC 3230: Instance Digests in HTTP]",
      "comments": "Obsoleted by [RFC 9530, Section 1.3: Digest Fields]"
    },
    {
      "name": "Repr-Digest",
      "status": "permanent",
      "structuredType": "Dictionary",
      "reference": "[RFC 9530, Section 3: Digest Fields]",
      "comments": null
    },
    {
      "name": "Unencoded-Digest",
      "status": "permanent",
      "structuredType": "Dictionary",
      "reference": "[RFC-ietf-httpbis-unencoded-digest-05, Section 3: HTTP Unencoded Digest]",
      "comments": null
    },
    {
      "name": "Want-Content-Digest",
      "status": "permanent",
      "structuredType": "Dictionary",
      "reference": "[RFC 9530, Section 4: Digest Fields]",
      "comments": null
    },
    {
      "name": "Want-Digest",
      "status": "obsoleted",
    …
    "generatedAt": "2026-07-29T08:13:22.000Z"
  }
}

GET /api/http-fields/lookup Look up one registered HTTP field name Single-record lookup

Route reference

Code, request parameters, response fields and verified examples 5 params · 5 fields · 2 examples

Code samples Ready-to-copy requests in 4 languages

curl JavaScript Python PHP

curl "https://randomapi.dev/api/http-fields/lookup?name=content-type"

const res = await fetch("https://randomapi.dev/api/http-fields/lookup?name=content-type");
const { data, meta } = await res.json();

import requests

data = requests.get("https://randomapi.dev/api/http-fields/lookup?name=content-type").json()["data"]

$json = json_decode(file_get_contents(
  "https://randomapi.dev/api/http-fields/lookup?name=content-type"
), true);
$data = $json["data"];

Parameters Route-specific request inputs 1

Parameter	Type	Default & allowed	Description
`name` required	string	allowed: 1 – 128 example: Content-Type	Registered HTTP field name; matching is case-insensitive.

name string required

Registered HTTP field name; matching is case-insensitive.

allowed: 1 – 128

example: name=Content-Type

Universal parameters Shared response and formatting options 4

Parameter	Type	Default & allowed	Description
`fields`	list	example: name,status	Return only these fields (comma-separated). Mutually exclusive with 'exclude'.
`exclude`	list	example: comments	Return all fields except these (comma-separated).
`pretty`	boolean	default: false example: true	Pretty-print the JSON response.
`unwrap`	boolean	default: false example: true	Drop the envelope: return the raw array/object without data/meta wrapper.

fields list

Return only these fields (comma-separated). Mutually exclusive with 'exclude'.

example: fields=name,status

exclude list

Return all fields except these (comma-separated).

example: exclude=comments

pretty boolean

Pretty-print the JSON response.

default: false

example: pretty=true

unwrap boolean

Drop the envelope: return the raw array/object without data/meta wrapper.

default: false

example: unwrap=true

Response schema Fields returned in each record 5

Field	Type	Description	Example
`name`	string	HTTP field name exactly as registered by IANA.	Accept
`status`	string	IANA registration status, preserving the source CSV's spelling.	permanent
`structuredType` nullable	string	RFC 9651 Structured Field type (Dictionary, List, Item or Token), or null when unregistered.	List
`reference`	string	Specification reference copied from the pinned IANA registry row.	[RFC 9110, Section 12.5.1: HTTP Semantics]
`comments` nullable	string	IANA registry comment, or null when the row has no comment.	(reserved)

name string

HTTP field name exactly as registered by IANA.

example: Accept

status string

IANA registration status, preserving the source CSV's spelling.

example: permanent

structuredType string nullable

RFC 9651 Structured Field type (Dictionary, List, Item or Token), or null when unregistered.

example: List

reference string

Specification reference copied from the pinned IANA registry row.

example: [RFC 9110, Section 12.5.1: HTTP Semantics]

comments string nullable

IANA registry comment, or null when the row has no comment.

example: (reserved)

Documented examples

Build-generated requests and complete responses 2

Look up Content-Type /api/http-fields/lookup?name=content-type

GET /api/http-fields/lookup?name=content-type

{
  "data": {
    "name": "Content-Type",
    "status": "permanent",
    "structuredType": null,
    "reference": "[RFC 9110, Section 8.3: HTTP Semantics]",
    "comments": null
  },
  "meta": {
    "endpoint": "http-fields",
    "route": "/lookup",
    "params": {
      "name": "Content-Type"
    },
    "generatedAt": "2026-07-29T08:13:22.000Z"
  }
}

Inspect the reserved wildcard row /api/http-fields/lookup?name=*

GET /api/http-fields/lookup?name=*

{
  "data": {
    "name": "*",
    "status": "permanent",
    "structuredType": null,
    "reference": "[RFC 9110, Section 12.5.5: HTTP Semantics]",
    "comments": "(reserved)"
  },
  "meta": {
    "endpoint": "http-fields",
    "route": "/lookup",
    "params": {
      "name": "*"
    },
    "generatedAt": "2026-07-29T08:13:22.000Z"
  }
}

About this API

Coverage, behavior and common use cases

Coverage & behavior

A complete, source-preserving snapshot of the IANA Hypertext Transfer Protocol Field Name Registry. Every CSV row is included, including permanent, provisional, deprecated and obsoleted names; the optional Structured Type column follows RFC 9651 and can be Dictionary, List, Item or Token.

The list route composes status, structuredType and free-text search filters. Status filtering is case-insensitive because four Fetch Metadata rows in the pinned IANA CSV spell Permanent with an uppercase P; the returned status deliberately preserves that source spelling instead of silently rewriting registry data. Lookup is case-insensitive because HTTP field names are case-insensitive.

This is a dated, bundled registry snapshot: it performs no request-time fetch. The committed refresh script downloads the IANA CSV and XML metadata, validates every column/status/type, records the CSV SHA-256 and regenerates the typed dataset deterministically.

Use it for

Validate field-name registries and documentation tooling against current IANA registrations
Find deprecated or obsoleted HTTP fields before modernizing a client or proxy
Discover which registered fields have an RFC 9651 Structured Field type

Frequently asked questions

Practical answers about this endpoint 4

Does this include every IANA HTTP field name?

Yes. The bundled snapshot contains every row in the pinned IANA Field Name CSV, with its source status, Structured Field type, reference and comment.

Are HTTP field-name lookups case-sensitive?

No. /lookup?name=content-type resolves the registered Content-Type row because HTTP field names are case-insensitive.

What does structuredType mean?

It is IANA's optional RFC 9651 classification: Dictionary, List, Item or Token. A null value means the registry has not assigned a Structured Field type.

How is the registry snapshot refreshed?

scripts/refresh-http-fields.mjs fetches the official CSV and XML metadata, validates the complete source and regenerates the typed file with its update date and SHA-256.

Standards & references

Primary sources behind the contract

Useful next tools in the catalog

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HTTP Methods Reference API REAL DATA

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HTTP Byte Range Parser API REAL DATA

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HTTP Structured Fields Parser API REAL DATA

Parse and serialize RFC 9651 structured field values — items, lists, dictionaries, parameters, dates and display strings — with exact type reporting.

GET /api/http-fields List and filter every registered HTTP field name Returns a list

Request parameters

Response

Route reference

Documented examples

GET /api/http-fields/lookup Look up one registered HTTP field name Single-record lookup

Request parameters

Response

Route reference

Documented examples

About this API

Coverage & behavior

Use it for

Frequently asked questions

Standards & references

Related APIs