Hypertext Transfer Protocol (HTTP) Field Name Registry
Hypertext Transfer Protocol (HTTP) Field Name Registry
Created
2021-10-01
2026-03-06
Available Formats
XML
HTML
Plain text
Registry Included Below
Hypertext Transfer Protocol (HTTP) Field Name Registry
Hypertext Transfer Protocol (HTTP) Field Name Registry
Registration Procedure(s)
Specification Required for Permanent registrations,
Expert Review for Provisional registrations.
Expert(s)
Mark Nottingham, Roy Fielding
Reference
RFC9110
][
RFC9651
Note
See Section 16.3 of [
RFC9110
] for more
information on defining and registering new HTTP Fields.
Note
New field names, along with changes to existing ones, can be
requested using the [
registry interface
] or the mailing list
defined in [
RFC9110
].
Note
The "Structured Type" column indicates the type of the field (per
RFC9651
]), if any, and may be "Dictionary", "List", or "Item".
Note that field names beginning with characters other than ALPHA
or "*" will not be able to be represented as a Structured Fields
Token and therefore may be incompatible with being mapped into
field values that refer to it.
Available Formats
CSV
Field Name
Status
Structured Type
Reference
Comments
A-IM
permanent
RFC 3229: Delta encoding in HTTP
Accept
permanent
RFC 9110, Section 12.5.1: HTTP Semantics
Accept-Additions
permanent
RFC 2324: Hyper Text Coffee Pot Control Protocol (HTCPCP/1.0)
Accept-CH
permanent
List
RFC 8942, Section 3.1: HTTP Client Hints
Accept-Charset
deprecated
RFC 9110, Section 12.5.2: HTTP Semantics
Accept-Datetime
permanent
RFC 7089: HTTP Framework for Time-Based Access to Resource States -- Memento
Accept-Encoding
permanent
RFC 9110, Section 12.5.3: HTTP Semantics
Accept-Features
permanent
RFC 2295: Transparent Content Negotiation in HTTP
Accept-Language
permanent
RFC 9110, Section 12.5.4: HTTP Semantics
Accept-Patch
permanent
RFC 5789: PATCH Method for HTTP
Accept-Post
permanent
Linked Data Platform 1.0
Accept-Query
permanent
List
RFC-ietf-httpbis-safe-method-w-body-14, Section 3: The HTTP QUERY Method
Accept-Ranges
permanent
RFC 9110, Section 14.3: HTTP Semantics
Accept-Signature
permanent
RFC 9421, Section 5.1: HTTP Message Signatures
Access-Control
obsoleted
Access Control for Cross-site Requests
Access-Control-Allow-Credentials
permanent
Fetch
Access-Control-Allow-Headers
permanent
Fetch
Access-Control-Allow-Methods
permanent
Fetch
Access-Control-Allow-Origin
permanent
Fetch
Access-Control-Expose-Headers
permanent
Fetch
Access-Control-Max-Age
permanent
Fetch
Access-Control-Request-Headers
permanent
Fetch
Access-Control-Request-Method
permanent
Fetch
Activate-Storage-Access
provisional
Item
Age
permanent
RFC 9111, Section 5.1: HTTP Caching
Allow
permanent
RFC 9110, Section 10.2.1: HTTP Semantics
ALPN
permanent
RFC 7639, Section 2: The ALPN HTTP Header Field
Alt-Svc
permanent
RFC 7838: HTTP Alternative Services
Alt-Used
permanent
RFC 7838: HTTP Alternative Services
Alternates
permanent
RFC 2295: Transparent Content Negotiation in HTTP
AMP-Cache-Transform
provisional
AMP-Cache-Transform HTTP request header
Apply-To-Redirect-Ref
permanent
RFC 4437: Web Distributed Authoring and Versioning (WebDAV) Redirect Reference Resources
Authentication-Control
permanent
RFC 8053, Section 4: HTTP Authentication Extensions for Interactive Clients
Authentication-Info
permanent
RFC 9110, Section 11.6.3: HTTP Semantics
Authorization
permanent
RFC 9110, Section 11.6.2: HTTP Semantics
Available-Dictionary
permanent
RFC 9842, Section 2.2: Compression Dictionary Transport
C-Ext
obsoleted
RFC 2774: An HTTP Extension Framework
Status change of HTTP experiments to Historic
C-Man
obsoleted
RFC 2774: An HTTP Extension Framework
Status change of HTTP experiments to Historic
C-Opt
obsoleted
RFC 2774: An HTTP Extension Framework
Status change of HTTP experiments to Historic
C-PEP
obsoleted
PEP - an Extension Mechanism for HTTP
Status change of HTTP experiments to Historic
C-PEP-Info
deprecated
PEP - an Extension Mechanism for HTTP
Status change of HTTP experiments to Historic
Cache-Control
permanent
RFC 9111, Section 5.2: HTTP Caching
Cache-Group-Invalidation
permanent
RFC9875: HTTP Cache Groups
Cache-Groups
permanent
RFC9875: HTTP Cache Groups
Cache-Status
permanent
List
RFC 9211: The Cache-Status HTTP Response Header Field
Cal-Managed-ID
permanent
RFC 8607, Section 5.1: Calendaring Extensions to WebDAV (CalDAV): Managed Attachments
CalDAV-Timezones
permanent
RFC 7809, Section 7.1: Calendaring Extensions to WebDAV (CalDAV): Time Zones by Reference
Capsule-Protocol
permanent
RFC 9297: HTTP Datagrams and the Capsule Protocol
CDN-Cache-Control
permanent
Dictionary
RFC 9213: Targeted HTTP Cache Control
Cache directives targeted at content delivery networks
CDN-Loop
permanent
RFC 8586: Loop Detection in Content Delivery Networks (CDNs)
Cert-Not-After
permanent
RFC 8739, Section 3.3: Support for Short-Term, Automatically Renewed (STAR) Certificates in the Automated Certificate Management Environment (ACME)
Cert-Not-Before
permanent
RFC 8739, Section 3.3: Support for Short-Term, Automatically Renewed (STAR) Certificates in the Automated Certificate Management Environment (ACME)
Clear-Site-Data
permanent
Clear Site Data
Client-Cert
permanent
Item
RFC 9440, Section 2: Client-Cert HTTP Header Field
Client-Cert-Chain
permanent
List
RFC 9440, Section 2: Client-Cert HTTP Header Field
Close
permanent
RFC 9112, Section 9.6: HTTP/1.1
(reserved)
CMCD-Object
provisional
CTA
][
CTA-5004 Common Media Client Data
CMCD-Request
provisional
CTA
][
CTA-5004 Common Media Client Data
CMCD-Session
provisional
CTA
][
CTA-5004 Common Media Client Data
CMCD-Status
provisional
CTA
][
CTA-5004 Common Media Client Data
CMSD-Dynamic
provisional
CTA
][
CTA-5006 Common Media Server Data (CMSD)
CMSD-Static
provisional
CTA
][
CTA-5006 Common Media Server Data (CMSD)
Concealed-Auth-Export
permanent
Item
RFC 9729: The Concealed HTTP Authentication Scheme
Configuration-Context
provisional
OSLC Configuration Management Version 1.0. Part 3: Configuration Specification
Connection
permanent
RFC 9110, Section 7.6.1: HTTP Semantics
Content-Base
obsoleted
RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1
Obsoleted by [
RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1
Content-Digest
permanent
RFC 9530, Section 2: Digest Fields
Content-Disposition
permanent
RFC 6266: Use of the Content-Disposition Header Field in the
Hypertext Transfer Protocol (HTTP)
Content-Encoding
permanent
RFC 9110, Section 8.4: HTTP Semantics
Content-ID
deprecated
The HTTP Distribution and Replication Protocol
Content-Language
permanent
RFC 9110, Section 8.5: HTTP Semantics
Content-Length
permanent
RFC 9110, Section 8.6: HTTP Semantics
Content-Location
permanent
RFC 9110, Section 8.7: HTTP Semantics
Content-MD5
obsoleted
RFC 2616, Section 14.15: Hypertext Transfer Protocol -- HTTP/1.1
Obsoleted by [
RFC 7231, Appendix B: Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content
Content-Range
permanent
RFC 9110, Section 14.4: HTTP Semantics
Content-Script-Type
obsoleted
HTML 4.01 Specification
Content-Security-Policy
permanent
Content Security Policy Level 3
Content-Security-Policy-Report-Only
permanent
Content Security Policy Level 3
Content-Style-Type
obsoleted
HTML 4.01 Specification
Content-Type
permanent
RFC 9110, Section 8.3: HTTP Semantics
Content-Version
obsoleted
RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1
permanent
RFC-ietf-httpbis-rfc6265bis-22, Section 5.8.1: Cookies: HTTP State Management Mechanism
Cookie2
obsoleted
RFC 2965: HTTP State Management Mechanism
Obsoleted by [
RFC 6265: HTTP State Management Mechanism
Cross-Origin-Embedder-Policy
permanent
Item
HTML
Cross-Origin-Embedder-Policy-Report-Only
permanent
Item
HTML
Cross-Origin-Opener-Policy
permanent
Item
HTML
Cross-Origin-Opener-Policy-Report-Only
permanent
Item
HTML
Cross-Origin-Resource-Policy
permanent
Fetch
CTA-Common-Access-Token
provisional
CTA
][
Chris_Lemmons
DASL
permanent
RFC 5323: Web Distributed Authoring and Versioning (WebDAV) SEARCH
Date
permanent
RFC 9110, Section 6.6.1: HTTP Semantics
DAV
permanent
RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV)
Default-Style
obsoleted
HTML 4.01 Specification
Delta-Base
permanent
RFC 3229: Delta encoding in HTTP
Deprecation
permanent
Item
RFC 9745, Section 2: The Deprecation HTTP Response Header Field
Depth
permanent
RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV)
Derived-From
obsoleted
RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1
Destination
permanent
RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV)
Detached-JWS
permanent
RFC 9635: Grant Negotiation and Authorization Protocol (GNAP)
Differential-ID
deprecated
The HTTP Distribution and Replication Protocol
Dictionary-ID
permanent
RFC 9842, Section 2.3: Compression Dictionary Transport
Digest
obsoleted
RFC 3230: Instance Digests in HTTP
Obsoleted by [
RFC 9530, Section 1.3: Digest Fields
DPoP
permanent
RFC 9449: OAuth 2.0 Demonstrating Proof of Possession (DPoP)
DPoP-Nonce
permanent
RFC 9449: OAuth 2.0 Demonstrating Proof of Possession (DPoP)
Early-Data
permanent
RFC 8470: Using Early Data in HTTP
EDIINT-Features
provisional
RFC 6017: Electronic Data Interchange - Internet Integration (EDIINT) Features Header Field
ETag
permanent
RFC 9110, Section 8.8.3: HTTP Semantics
Expect
permanent
RFC 9110, Section 10.1.1: HTTP Semantics
Expect-CT
deprecated
RFC 9163: Expect-CT Extension for HTTP
Obsoleted by [
IESG
HTTPBIS
Expires
permanent
RFC 9111, Section 5.3: HTTP Caching
Ext
obsoleted
RFC 2774: An HTTP Extension Framework
Status change of HTTP experiments to Historic
Forwarded
permanent
RFC 7239: Forwarded HTTP Extension
From
permanent
RFC 9110, Section 10.1.2: HTTP Semantics
GetProfile
obsoleted
Implementation of OPS Over HTTP
Hobareg
permanent
RFC 7486, Section 6.1.1: HTTP Origin-Bound Authentication (HOBA)
Host
permanent
RFC 9110, Section 7.2: HTTP Semantics
HTTP2-Settings
obsoleted
RFC 7540, Section 3.2.1: Hypertext Transfer Protocol Version 2 (HTTP/2)
Obsolete; see Section 11.1 of [
RFC9113
If
permanent
RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV)
If-Match
permanent
RFC 9110, Section 13.1.1: HTTP Semantics
If-Modified-Since
permanent
RFC 9110, Section 13.1.3: HTTP Semantics
If-None-Match
permanent
RFC 9110, Section 13.1.2: HTTP Semantics
If-Range
permanent
RFC 9110, Section 13.1.5: HTTP Semantics
If-Schedule-Tag-Match
permanent
RFC 6338: Scheduling Extensions to CalDAV
If-Unmodified-Since
permanent
RFC 9110, Section 13.1.4: HTTP Semantics
IM
permanent
RFC 3229: Delta encoding in HTTP
Include-Referred-Token-Binding-ID
permanent
RFC 8473: Token Binding over HTTP
Incremental
permanent
RFC-ietf-httpbis-incremental-04: Incremental Forwarding of HTTP Messages
Isolation
provisional
OData Version 4.01 Part 1: Protocol
][
OASIS
][
Chet_Ensign
Keep-Alive
permanent
RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1
Label
permanent
RFC 3253: Versioning Extensions to WebDAV: (Web Distributed Authoring and Versioning)
Last-Event-ID
permanent
HTML
Last-Modified
permanent
RFC 9110, Section 8.8.2: HTTP Semantics
Link
permanent
RFC 8288: Web Linking
Link-Template
permanent
RFC 9652: The Link-Template HTTP Header Field
Location
permanent
RFC 9110, Section 10.2.2: HTTP Semantics
Lock-Token
permanent
RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV)
Man
obsoleted
RFC 2774: An HTTP Extension Framework
Status change of HTTP experiments to Historic
Max-Forwards
permanent
RFC 9110, Section 7.6.2: HTTP Semantics
Memento-Datetime
permanent
RFC 7089: HTTP Framework for Time-Based Access to Resource States -- Memento
Meter
permanent
RFC 2227: Simple Hit-Metering and Usage-Limiting for HTTP
Method-Check
obsoleted
Access Control for Cross-site Requests
Method-Check-Expires
obsoleted
Access Control for Cross-site Requests
MIME-Version
permanent
RFC 9112, Appendix B.1: HTTP/1.1
Negotiate
permanent
RFC 2295: Transparent Content Negotiation in HTTP
NEL
permanent
Network Error Logging
OData-EntityId
permanent
OData Version 4.01 Part 1: Protocol
][
OASIS
][
Chet_Ensign
OData-Isolation
permanent
OData Version 4.01 Part 1: Protocol
][
OASIS
][
Chet_Ensign
OData-MaxVersion
permanent
OData Version 4.01 Part 1: Protocol
][
OASIS
][
Chet_Ensign
OData-Version
permanent
OData Version 4.01 Part 1: Protocol
][
OASIS
][
Chet_Ensign
Opt
obsoleted
RFC 2774: An HTTP Extension Framework
Status change of HTTP experiments to Historic
Optional-WWW-Authenticate
permanent
RFC 8053, Section 3: HTTP Authentication Extensions for Interactive Clients
Ordering-Type
permanent
RFC 3648: Web Distributed Authoring and Versioning (WebDAV) Ordered Collections Protocol
Origin
permanent
RFC 6454: The Web Origin Concept
Origin-Agent-Cluster
permanent
Item
HTML
OSCORE
permanent
RFC 8613, Section 11.1: Object Security for Constrained RESTful Environments (OSCORE)
OSLC-Core-Version
permanent
OASIS Project Specification 01
][
OASIS
][
Chet_Ensign
Overwrite
permanent
RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV)
P3P
obsoleted
The Platform for Privacy Preferences 1.0 (P3P1.0) Specification
PEP
obsoleted
PEP - an Extension Mechanism for HTTP
PEP-Info
obsoleted
PEP - an Extension Mechanism for HTTP
Permissions-Policy
provisional
Permissions Policy
PICS-Label
obsoleted
PICS Label Distribution Label Syntax and Communication Protocols
Ping-From
permanent
HTML
Ping-To
permanent
HTML
Position
permanent
RFC 3648: Web Distributed Authoring and Versioning (WebDAV) Ordered Collections Protocol
Pragma
deprecated
RFC 9111, Section 5.4: HTTP Caching
Prefer
permanent
RFC 7240: Prefer Header for HTTP
Preference-Applied
permanent
RFC 7240: Prefer Header for HTTP
Priority
permanent
Dictionary
RFC 9218: Extensible Prioritization Scheme for HTTP
ProfileObject
obsoleted
Implementation of OPS Over HTTP
Protocol
obsoleted
PICS Label Distribution Label Syntax and Communication Protocols
Protocol-Info
deprecated
White Paper: Joint Electronic Payment Initiative
Protocol-Query
deprecated
White Paper: Joint Electronic Payment Initiative
Protocol-Request
obsoleted
PICS Label Distribution Label Syntax and Communication Protocols
Proxy-Authenticate
permanent
RFC 9110, Section 11.7.1: HTTP Semantics
Proxy-Authentication-Info
permanent
RFC 9110, Section 11.7.3: HTTP Semantics
Proxy-Authorization
permanent
RFC 9110, Section 11.7.2: HTTP Semantics
Proxy-Features
obsoleted
Notification for Proxy Caches
Proxy-Instruction
obsoleted
Notification for Proxy Caches
Proxy-Status
permanent
List
RFC 9209: The Proxy-Status HTTP Response Header Field
Public
obsoleted
RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1
Public-Key-Pins
permanent
RFC 7469: Public Key Pinning Extension for HTTP
Public-Key-Pins-Report-Only
permanent
RFC 7469: Public Key Pinning Extension for HTTP
Range
permanent
RFC 9110, Section 14.2: HTTP Semantics
Redirect-Ref
permanent
RFC 4437: Web Distributed Authoring and Versioning (WebDAV) Redirect Reference Resources
Referer
permanent
RFC 9110, Section 10.1.3: HTTP Semantics
Referer-Root
obsoleted
Access Control for Cross-site Requests
Referrer-Policy
permanent
Referrer Policy
The header name does not share the HTTP Referer header's misspelling.
Refresh
permanent
HTML
Repeatability-Client-ID
provisional
Repeatable Requests Version 1.0
][
OASIS
][
Chet_Ensign
Repeatability-First-Sent
provisional
Repeatable Requests Version 1.0
][
OASIS
][
Chet_Ensign
Repeatability-Request-ID
provisional
Repeatable Requests Version 1.0
][
OASIS
][
Chet_Ensign
Repeatability-Result
provisional
Repeatable Requests Version 1.0
][
OASIS
][
Chet_Ensign
Replay-Nonce
permanent
RFC 8555, Section 6.5.1: Automatic Certificate Management Environment (ACME)
Reporting-Endpoints
provisional
Reporting API
Repr-Digest
permanent
RFC 9530, Section 3: Digest Fields
Retry-After
permanent
RFC 9110, Section 10.2.3: HTTP Semantics
Safe
obsoleted
RFC 2310: The Safe Response Header Field
Status change of HTTP experiments to Historic
Schedule-Reply
permanent
RFC 6638: Scheduling Extensions to CalDAV
Schedule-Tag
permanent
RFC 6338: Scheduling Extensions to CalDAV
Sec-Fetch-Dest
Permanent
Item
Sec-Fetch-Mode
Permanent
Item
Sec-Fetch-Site
Permanent
Item
Sec-Fetch-Storage-Access
provisional
Token
Sec-Fetch-User
Permanent
Item
Sec-GPC
provisional
Global Privacy Control (GPC)
Sec-Purpose
permanent
Fetch
Intended to replace the (not registered) Purpose and x-moz headers.
Sec-Token-Binding
permanent
RFC 8473: Token Binding over HTTP
Sec-WebSocket-Accept
permanent
RFC 6455: The WebSocket Protocol
Sec-WebSocket-Extensions
permanent
RFC 6455: The WebSocket Protocol
Sec-WebSocket-Key
permanent
RFC 6455: The WebSocket Protocol
Sec-WebSocket-Protocol
permanent
RFC 6455: The WebSocket Protocol
Sec-WebSocket-Version
permanent
RFC 6455: The WebSocket Protocol
Security-Scheme
obsoleted
RFC 2660: The Secure HyperText Transfer Protocol
Status change of HTTP experiments to Historic
Server
permanent
RFC 9110, Section 10.2.4: HTTP Semantics
Server-Timing
permanent
Server Timing
Set-Cookie
permanent
RFC-ietf-httpbis-rfc6265bis-22, Section 5.8.1: Cookies: HTTP State Management Mechanism
Set-Cookie2
obsoleted
RFC 2965: HTTP State Management Mechanism
Obsoleted by [
RFC 6265: HTTP State Management Mechanism
Set-Txn
permanent
RFC-ietf-scim-events-15, Section 3: SCIM Profile for Security Event Tokens
SetProfile
obsoleted
Implementation of OPS Over HTTP
Signature
permanent
RFC 9421, Section 4.2: HTTP Message Signatures
Signature-Input
permanent
RFC 9421, Section 4.1: HTTP Message Signatures
SLUG
permanent
RFC 5023: The Atom Publishing Protocol
SoapAction
permanent
Simple Object Access Protocol (SOAP) 1.1
Status-URI
permanent
RFC 2518: HTTP Extensions for Distributed Authoring -- WEBDAV
Strict-Transport-Security
permanent
RFC 6797: HTTP Strict Transport Security (HSTS)
Sunset
permanent
RFC 8594: The Sunset HTTP Header Field
Surrogate-Capability
provisional
Edge Architecture Specification
Surrogate-Control
provisional
Edge Architecture Specification
TCN
permanent
RFC 2295: Transparent Content Negotiation in HTTP
TE
permanent
RFC 9110, Section 10.1.4: HTTP Semantics
Timeout
permanent
RFC 4918: HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV)
Timing-Allow-Origin
provisional
Resource Timing Level 1
Topic
permanent
RFC 8030, Section 5.4: Generic Event Delivery Using HTTP Push
Traceparent
permanent
Trace Context
Tracestate
permanent
Trace Context
Trailer
permanent
RFC 9110, Section 6.6.2: HTTP Semantics
Transfer-Encoding
permanent
RFC 9112, Section 6.1: HTTP Semantics
TTL
permanent
RFC 8030, Section 5.2: Generic Event Delivery Using HTTP Push
Upgrade
permanent
RFC 9110, Section 7.8: HTTP Semantics
Urgency
permanent
RFC 8030, Section 5.3: Generic Event Delivery Using HTTP Push
URI
obsoleted
RFC 2068: Hypertext Transfer Protocol -- HTTP/1.1
Use-As-Dictionary
permanent
RFC 9842, Section 2.1: Compression Dictionary Transport
User-Agent
permanent
RFC 9110, Section 10.1.5: HTTP Semantics
Variant-Vary
permanent
RFC 2295: Transparent Content Negotiation in HTTP
Vary
permanent
RFC 9110, Section 12.5.5: HTTP Semantics
Via
permanent
RFC 9110, Section 7.6.3: HTTP Semantics
Want-Content-Digest
permanent
RFC 9530, Section 4: Digest Fields
Want-Digest
obsoleted
RFC 3230: Instance Digests in HTTP
Obsoleted by [
RFC 9530, Section 1.3: Digest Fields
Want-Repr-Digest
permanent
RFC 9530, Section 4: Digest Fields
Warning
obsoleted
RFC 9111, Section 5.5: HTTP Caching
WWW-Authenticate
permanent
RFC 9110, Section 11.6.1: HTTP Semantics
X-Content-Type-Options
permanent
Fetch
X-Frame-Options
permanent
HTML
permanent
RFC 9110, Section 12.5.5: HTTP Semantics
(reserved)
Contact Information
ID
Name
Organization
Contact URI
[Chet_Ensign]
Chet Ensign
mailto:chet.ensign&oasis-open.org
2020-09-01
[Chris_Lemmons]
Chris Lemmons
mailto:Chris_Lemmons&comcast.com
2024-08-06
[CTA]
Consumer Technology Association
mailto:standards&cta.tech
2024-08-07
[OASIS]
OASIS