2021-10-01 2026-03-06 Specification Required for Permanent registrations, Expert Review for Provisional registrations. Mark Nottingham, Roy Fielding See Section 16.3 of for more information on defining and registering new HTTP Fields. New field names, along with changes to existing ones, can be requested using the registry interface or the mailing list defined in . The "Structured Type" column indicates the type of the field (per ), 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. 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-5004 Common Media Client Data CMCD-Request provisional CTA-5004 Common Media Client Data CMCD-Session provisional CTA-5004 Common Media Client Data CMCD-Status provisional CTA-5004 Common Media Client Data CMSD-Dynamic provisional CTA-5006 Common Media Server Data (CMSD) CMSD-Static provisional 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 Cookie 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 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 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 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 OData-Isolation permanent OData Version 4.01 Part 1: Protocol OData-MaxVersion permanent OData Version 4.01 Part 1: Protocol OData-Version permanent OData Version 4.01 Part 1: Protocol 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 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 Repeatability-First-Sent provisional Repeatable Requests Version 1.0 Repeatability-Request-ID provisional Repeatable Requests Version 1.0 Repeatability-Result provisional Repeatable Requests Version 1.0 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) Chet Ensign mailto:chet.ensign&oasis-open.org 2020-09-01 Chris Lemmons mailto:Chris_Lemmons&comcast.com 2024-08-06 Consumer Technology Association mailto:standards&cta.tech 2024-08-07 OASIS https://www.oasis-open.org