134 registered link relations. HTML acts on 26 of them.

Check a rel attribute

The rel value

On which element

Every keyword is judged against the element you picked, because the same word can be meaningful on one and ignored on another.

noopenerAnnotation

Indicates that any newly created top-level browsing context which results from following the link will not be an auxiliary browsing context.

noreferrerAnnotation

Indicates that no referrer information is to be leaked when following the link.

stylesheetIgnored on this element

HTML defines this keyword, but not for the element you chose.

describedbyRegistered, but not a markup keyword

IANA registers it and HTML says nothing about it. That is not an error — it is a perfectly good value in an HTTP Link header or in a feed, just not something a browser acts on in markup.

The two sources, side by side

keywords in total: 135
in the IANA registry: 134
in the HTML Standard: 27
registered, absent from HTML: 108

The registry and the markup vocabulary are not the same list. 108 registered relations appear nowhere in the HTML Standard, and one HTML keyword — expect, for render-blocking — is not registered at all. It is also the table's only Internal Resource.

Where a keyword goes matters as much as whether it exists. stylesheet is an External Resource on a link element and is allowed nowhere else; the noopener, noreferrer, opener, nofollow, external, bookmark and tag family is allowed only away from link. No keyword is ever an External Resource outside link, and no Annotation is ever allowed on it.

Seven keywords are body-ok, meaning a link element carrying them is valid inside body rather than only in head: dns-prefetch, modulepreload, pingback, preconnect, prefetch, preload and stylesheet. Two of them, preconnect and preload, also have defined processing in an HTTP Link header.

Every keyword from both sources

Showing 135 / 135

Keyword	link	a / area	form	Description
about	not in HTML	not in HTML	not in HTML	Refers to a resource that is the subject of the link's context.
acl	not in HTML	not in HTML	not in HTML	Asserts that the link target provides an access control resource for the link context.
alternate	Hyperlink	Hyperlink	—	Refers to a substitute for this context
amphtml	not in HTML	not in HTML	not in HTML	Used to reference alternative content that uses the AMP profile of the HTML format.
api-catalog	not in HTML	not in HTML	not in HTML	Refers to a list of APIs available from the Publisher of the link context.
appendix	not in HTML	not in HTML	not in HTML	Refers to an appendix.
apple-touch-icon	not in HTML	not in HTML	not in HTML	Refers to an icon for the context. Synonym for icon.
apple-touch-startup-image	not in HTML	not in HTML	not in HTML	Refers to a launch screen for the context.
archives	not in HTML	not in HTML	not in HTML	Refers to a collection of records, documents, or other materials of historical interest.
author	Hyperlink	Hyperlink	—	Refers to the context's author.
blocked-by	not in HTML	not in HTML	not in HTML	Identifies the entity that blocks access to a resource following receipt of a legal demand.
bookmark	—	Hyperlink	—	Gives a permanent link to use for bookmarking purposes.
c2pa-manifest	not in HTML	not in HTML	not in HTML	This link relation identifies the C2PA Manifest associated with the link context
canonical	Hyperlink	—	—	Designates the preferred version of a resource (the IRI and its contents).
chapter	not in HTML	not in HTML	not in HTML	Refers to a chapter in a collection of resources.
cite-as	not in HTML	not in HTML	not in HTML	Indicates that the link target is preferred over the link context for the purpose of permanent citation.
collection	not in HTML	not in HTML	not in HTML	The target IRI points to a resource which represents the collection resource for the context IRI.
compression-dictionary	not in HTML	not in HTML	not in HTML	Refers to a compression dictionary used for content encoding.
contents	not in HTML	not in HTML	not in HTML	Refers to a table of contents.
convertedfrom	not in HTML	not in HTML	not in HTML	The document linked to was later converted to the document that contains this link relation. For example, an RFC can have a link to the Internet-Draft that became the RFC; in that case, the link relation would be "convertedFrom".
copyright	not in HTML	not in HTML	not in HTML	Refers to a copyright statement that applies to the link's context.
create-form	not in HTML	not in HTML	not in HTML	The target IRI points to a resource where a submission form can be obtained.
current	not in HTML	not in HTML	not in HTML	Refers to a resource containing the most recent item(s) in a collection of resources.
deprecation	not in HTML	not in HTML	not in HTML	Refers to documentation (intended for human consumption) about the deprecation of the link's context.
describedby	not in HTML	not in HTML	not in HTML	Refers to a resource providing information about the link's context.
describes	not in HTML	not in HTML	not in HTML	The relationship A 'describes' B asserts that resource A provides a description of resource B. There are no constraints on the format or representation of either A or B, neither are there any further constraints on either resource.
disclosure	not in HTML	not in HTML	not in HTML	Refers to a list of patent disclosures made with respect to material for which 'disclosure' relation is specified.
dns-prefetch	External Resource	—	—	Used to indicate an origin that will be used to fetch required resources for the link context, and that the user agent ought to resolve as early as possible.
dpp	not in HTML	not in HTML	not in HTML	A link from a context URI that identifies a product to its digital product passport
duplicate	not in HTML	not in HTML	not in HTML	Refers to a resource whose available representations are byte-for-byte identical with the corresponding representations of the context IRI.
edit	not in HTML	not in HTML	not in HTML	Refers to a resource that can be used to edit the link's context.
edit-form	not in HTML	not in HTML	not in HTML	The target IRI points to a resource where a submission form for editing associated resource can be obtained.
edit-media	not in HTML	not in HTML	not in HTML	Refers to a resource that can be used to edit media associated with the link's context.
enclosure	not in HTML	not in HTML	not in HTML	Identifies a related resource that is potentially large and might require special handling.
expectnot registered	Internal Resource	—	—	Expect an element with the target ID to appear in the current document.
external	—	Annotation	Annotation	Refers to a resource that is not part of the same site as the current context.
first	not in HTML	not in HTML	not in HTML	An IRI that refers to the furthest preceding resource in a series of resources.
geofeed	not in HTML	not in HTML	not in HTML	Refers to a resource with IP geofeed location information related to the link context.
glossary	not in HTML	not in HTML	not in HTML	Refers to a glossary of terms.
help	Hyperlink	Hyperlink	Hyperlink	Refers to context-sensitive help.
hosts	not in HTML	not in HTML	not in HTML	Refers to a resource hosted by the server indicated by the link context.
hub	not in HTML	not in HTML	not in HTML	Refers to a hub that enables registration for notification of updates to the context.
ice-server	not in HTML	not in HTML	not in HTML	Conveys the STUN and TURN servers that can be used by an ICE agent to establish a connection with a peer.
icon	External Resource	—	—	Refers to an icon representing the link's context.
index	not in HTML	not in HTML	not in HTML	Refers to an index.
intervalafter	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval that ends before the beginning of the time interval associated with the context resource
intervalbefore	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval that begins after the end of the time interval associated with the context resource
intervalcontains	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval that begins after the beginning of the time interval associated with the context resource, and ends before the end of the time interval associated with the context resource
intervaldisjoint	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval that begins after the end of the time interval associated with the context resource, or ends before the beginning of the time interval associated with the context resource
intervalduring	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval that begins before the beginning of the time interval associated with the context resource, and ends after the end of the time interval associated with the context resource
intervalequals	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval whose beginning coincides with the beginning of the time interval associated with the context resource, and whose end coincides with the end of the time interval associated with the context resource
intervalfinishedby	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval that begins after the beginning of the time interval associated with the context resource, and whose end coincides with the end of the time interval associated with the context resource
intervalfinishes	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval that begins before the beginning of the time interval associated with the context resource, and whose end coincides with the end of the time interval associated with the context resource
intervalin	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval that begins before or is coincident with the beginning of the time interval associated with the context resource, and ends after or is coincident with the end of the time interval associated with the context resource
intervalmeets	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval whose beginning coincides with the end of the time interval associated with the context resource
intervalmetby	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval whose end coincides with the beginning of the time interval associated with the context resource
intervaloverlappedby	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval that begins before the beginning of the time interval associated with the context resource, and ends after the beginning of the time interval associated with the context resource
intervaloverlaps	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval that begins before the end of the time interval associated with the context resource, and ends after the end of the time interval associated with the context resource
intervalstartedby	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval whose beginning coincides with the beginning of the time interval associated with the context resource, and ends before the end of the time interval associated with the context resource
intervalstarts	not in HTML	not in HTML	not in HTML	refers to a resource associated with a time interval whose beginning coincides with the beginning of the time interval associated with the context resource, and ends after the end of the time interval associated with the context resource
item	not in HTML	not in HTML	not in HTML	The target IRI points to a resource that is a member of the collection represented by the context IRI.
last	not in HTML	not in HTML	not in HTML	An IRI that refers to the furthest following resource in a series of resources.
latest-version	not in HTML	not in HTML	not in HTML	Points to a resource containing the latest (e.g., current) version of the context.
license	Hyperlink	Hyperlink	Hyperlink	Refers to a license associated with this context.
linkset	not in HTML	not in HTML	not in HTML	The link target of a link with the "linkset" relation type provides a set of links, including links in which the link context of the link participates.
lrdd	not in HTML	not in HTML	not in HTML	Refers to further information about the link's context, expressed as a LRDD ("Link-based Resource Descriptor Document") resource. See [RFC6415] for information about processing this relation type in host-meta documents. When used elsewhere, it refers to additional links and other metadata. Multiple instances indicate additional LRDD resources. LRDD resources MUST have an "application/xrd+xml" representation, and MAY have others.
manifest	External Resource	—	—	Links to a manifest file for the context.
mask-icon	not in HTML	not in HTML	not in HTML	Refers to a mask that can be applied to the icon for the context.
me	not in HTML	not in HTML	not in HTML	Links to a resource about the author of the link's context.
media-feed	not in HTML	not in HTML	not in HTML	Refers to a feed of personalised media recommendations relevant to the link context.
memento	not in HTML	not in HTML	not in HTML	The Target IRI points to a Memento, a fixed resource that will not change state anymore.
micropub	not in HTML	not in HTML	not in HTML	Links to the context's Micropub endpoint.
modulepreload	External Resource	—	—	Refers to a module that the user agent is to preemptively fetch and store for use in the current context.
monitor	not in HTML	not in HTML	not in HTML	Refers to a resource that can be used to monitor changes in an HTTP resource.
monitor-group	not in HTML	not in HTML	not in HTML	Refers to a resource that can be used to monitor changes in a specified group of HTTP resources.
next	Hyperlink	Hyperlink	Hyperlink	Indicates that the link's context is a part of a series, and that the next in the series is the link target.
next-archive	not in HTML	not in HTML	not in HTML	Refers to the immediately following archive resource.
nofollow	—	Annotation	Annotation	Indicates that the context’s original author or publisher does not endorse the link target.
noopener	—	Annotation	Annotation	Indicates that any newly created top-level browsing context which results from following the link will not be an auxiliary browsing context.
noreferrer	—	Annotation	Annotation	Indicates that no referrer information is to be leaked when following the link.
opener	—	Annotation	Annotation	Indicates that any newly created top-level browsing context which results from following the link will be an auxiliary browsing context.
openid2.local_id	not in HTML	not in HTML	not in HTML	Refers to an OpenID Authentication server on which the context relies for an assertion that the end user controls an Identifier.
openid2.provider	not in HTML	not in HTML	not in HTML	Refers to a resource which accepts OpenID Authentication protocol messages for the context.
original	not in HTML	not in HTML	not in HTML	The Target IRI points to an Original Resource.
p3pv1	not in HTML	not in HTML	not in HTML	Refers to a P3P privacy policy for the context.
payment	not in HTML	not in HTML	not in HTML	Indicates a resource where payment is accepted.
pingback	External Resource	—	—	Gives the address of the pingback resource for the link context.
preconnect	External Resource	—	—	Used to indicate an origin that will be used to fetch required resources for the link context. Initiating an early connection, which includes the DNS lookup, TCP handshake, and optional TLS negotiation, allows the user agent to mask the high latency costs of establishing a connection.
predecessor-version	not in HTML	not in HTML	not in HTML	Points to a resource containing the predecessor version in the version history.
prefetch	External Resource	—	—	The prefetch link relation type is used to identify a resource that might be required by the next navigation from the link context, and that the user agent ought to fetch, such that the user agent can deliver a faster response once the resource is requested in the future.
preload	External Resource	—	—	Refers to a resource that should be loaded early in the processing of the link's context, without blocking rendering.
prerender	not in HTML	not in HTML	not in HTML	Used to identify a resource that might be required by the next navigation from the link context, and that the user agent ought to fetch and execute, such that the user agent can deliver a faster response once the resource is requested in the future.
prev	Hyperlink	Hyperlink	Hyperlink	Indicates that the link's context is a part of a series, and that the previous in the series is the link target.
prev-archive	not in HTML	not in HTML	not in HTML	Refers to the immediately preceding archive resource.
preview	not in HTML	not in HTML	not in HTML	Refers to a resource that provides a preview of the link's context.
previous	not in HTML	not in HTML	not in HTML	Refers to the previous resource in an ordered series of resources. Synonym for "prev".
privacy-policy	Hyperlink	Hyperlink	—	Refers to a privacy policy associated with the link's context.
profile	not in HTML	not in HTML	not in HTML	Identifying that a resource representation conforms to a certain profile, without affecting the non-profile semantics of the resource representation.
publication	not in HTML	not in HTML	not in HTML	Links to a publication manifest. A manifest represents structured information about a publication, such as informative metadata, a list of resources, and a default reading order.
rdap-active	not in HTML	not in HTML	not in HTML	The target is for an RDAP RIR search that filters for the status "active".
rdap-bottom	not in HTML	not in HTML	not in HTML	Refers to the set of child RDAP objects that do not themselves have child objects, in a hierarchy of objects.
rdap-down	not in HTML	not in HTML	not in HTML	Refers to a set of RDAP child objects in a hierarchy of objects.
rdap-top	not in HTML	not in HTML	not in HTML	Refers to the topmost RDAP parent object in a hierarchy of objects.
rdap-up	not in HTML	not in HTML	not in HTML	Refers to an RDAP parent object in a hierarchy of objects.
related	not in HTML	not in HTML	not in HTML	Identifies a related resource.
replies	not in HTML	not in HTML	not in HTML	Identifies a resource that is a reply to the context of the link.
restconf	not in HTML	not in HTML	not in HTML	Identifies the root of RESTCONF API as configured on this HTTP server. The "restconf" relation defines the root of the API defined in RFC8040. Subsequent revisions of RESTCONF will use alternate relation values to support protocol versioning.
ruleinput	not in HTML	not in HTML	not in HTML	The resource identified by the link target provides an input value to an instance of a rule, where the resource which represents the rule instance is identified by the link context.
search	Hyperlink	Hyperlink	Hyperlink	Refers to a resource that can be used to search through the link's context and related resources.
section	not in HTML	not in HTML	not in HTML	Refers to a section in a collection of resources.
self	not in HTML	not in HTML	not in HTML	Conveys an identifier for the link's context.
service	not in HTML	not in HTML	not in HTML	Indicates a URI that can be used to retrieve a service document.
service-desc	not in HTML	not in HTML	not in HTML	Identifies service description for the context that is primarily intended for consumption by machines.
service-doc	not in HTML	not in HTML	not in HTML	Identifies service documentation for the context that is primarily intended for human consumption.
service-meta	not in HTML	not in HTML	not in HTML	Identifies general metadata for the context that is primarily intended for consumption by machines.
sip-trunking-capability	not in HTML	not in HTML	not in HTML	Refers to a capability set document that defines parameters or configuration requirements for automated peering and communication-channel negotiation of the Session Initiation Protocol (SIP).
sponsored	not in HTML	not in HTML	not in HTML	Refers to a resource that is within a context that is sponsored (such as advertising or another compensation agreement).
start	not in HTML	not in HTML	not in HTML	Refers to the first resource in a collection of resources.
status	not in HTML	not in HTML	not in HTML	Identifies a resource that represents the context's status.
stylesheet	External Resource	—	—	Refers to a stylesheet.
subsection	not in HTML	not in HTML	not in HTML	Refers to a resource serving as a subsection in a collection of resources.
successor-version	not in HTML	not in HTML	not in HTML	Points to a resource containing the successor version in the version history.
sunset	not in HTML	not in HTML	not in HTML	Identifies a resource that provides information about the context's retirement policy.
tag	—	Hyperlink	—	Gives a tag (identified by the given address) that applies to the current document.
terms-of-service	Hyperlink	Hyperlink	—	Refers to the terms of service associated with the link's context.
timegate	not in HTML	not in HTML	not in HTML	The Target IRI points to a TimeGate for an Original Resource.
timemap	not in HTML	not in HTML	not in HTML	The Target IRI points to a TimeMap for an Original Resource.
type	not in HTML	not in HTML	not in HTML	Refers to a resource identifying the abstract semantic type of which the link's context is considered to be an instance.
ugc	not in HTML	not in HTML	not in HTML	Refers to a resource that is within a context that is User Generated Content.
up	not in HTML	not in HTML	not in HTML	Refers to a parent document in a hierarchy of documents.
version-history	not in HTML	not in HTML	not in HTML	Points to a resource containing the version history for the context.
via	not in HTML	not in HTML	not in HTML	Identifies a resource that is the source of the information in the link's context.
webmention	not in HTML	not in HTML	not in HTML	Identifies a target URI that supports the Webmention protocol. This allows clients that mention a resource in some form of publishing process to contact that endpoint and inform it that this resource has been mentioned.
working-copy	not in HTML	not in HTML	not in HTML	Points to a working copy for this resource.
working-copy-of	not in HTML	not in HTML	not in HTML	Points to the versioned resource from which this working copy was obtained.

Relations and descriptions from the IANA Link Relation Types registry; the allowed-on columns from the HTML Standard's link types table. Nothing is uploaded — the check runs in this tab. Snapshot taken 2026-08-03

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Link relations: every rel value, and where each one works

The IANA registry and the HTML Standard's link types side by side, with the column that decides whether your rel attribute does anything.

What is a link relation?

A link relation is the value of a rel attribute: the stylesheet in a link element, the noopener on an anchor, the canonical that tells search engines which URL to prefer. It says what the thing at the other end of the link is to the thing containing it.

IANA keeps the register of them, 134 at the time this page was generated, each with a description and a defining document. Unlike some registries it has no status column — there is no Permanent or Provisional here, a relation is simply registered or it is not.

The HTML Standard keeps a separate, much shorter table of 27 link types, and that table carries the column the registry does not have: which element each keyword is allowed on. That column is what decides whether the rel attribute you just wrote does anything at all.

How to use it

Paste a rel value. The whole attribute, not one keyword — rel takes a space-separated set, and this splits it the way HTML does, on any whitespace.
Pick the element it sits on. link, a and area, or form. The same keyword can be meaningful on one and completely inert on another, so the element is not a detail.
Read the verdict per keyword. You get what it does there, or which of three quite different kinds of nothing it does: ignored on this element, registered but not a markup keyword, or in neither source.

The registry is not the list of rel values

Line the two sources up and only 26 names appear in both. That leaves 108 registered relations — four fifths of the registry — that the HTML Standard never mentions. They are not mistakes: relations like describedby, api-catalog and predecessor-version are real, defined by their own RFCs, and correct in an HTTP Link header or in an Atom feed. They are simply not markup keywords, and a browser rendering a page does nothing with them.

The traffic runs the other way too, for exactly one keyword. expect, which HTML uses for render-blocking, is not in the IANA registry. It is also the only entry in the whole table classed as an Internal Resource, every other keyword being a Hyperlink, an External Resource or an Annotation.

So a page listing the IANA registry under a heading like all the rel values you can use is wrong about 108 rows, and a page listing HTML's table as the link relations is wrong about 108 others. This one keeps both and marks which source each row came from.

Where a keyword goes matters as much as whether it exists

rel="stylesheet" on an anchor does nothing. stylesheet is an External Resource on a link element and is not allowed anywhere else — and that generalises: no keyword is ever an External Resource outside link, which makes sense once you notice that fetching a subresource is what link elements are for.

rel="noopener" on a link element does nothing either. The whole noopener, noreferrer, opener, nofollow, external, bookmark and tag family is allowed only away from link — seven keywords in total — because they annotate a navigation the user might perform, and a link element is not one. The mirror of the earlier rule holds as well: no Annotation is ever allowed on a link element.

Two more distinctions worth knowing. Seven keywords are body-ok, meaning a link element carrying them is valid inside body rather than only in head: dns-prefetch, modulepreload, pingback, preconnect, prefetch, preload and stylesheet. And just two of the 27, preconnect and preload, have defined processing when they arrive in an HTTP Link header instead of in markup.

What this page will not tell you

It will not tell you a rel value is invalid. HTML ignores keywords it does not recognise, by design, so an unknown value breaks nothing — it simply has no effect. Microformats and site-specific conventions rely on that, which is why this page reports what each keyword does rather than passing or failing your attribute.

It does not cover search engines' own conventions beyond what the two sources say. Google and others act on values like sponsored and ugc in ways their documentation defines, not the HTML Standard, so their behaviour is outside what is verified here.

And the registry is a snapshot, dated under the table. Relations are added continuously, so a very new one may be missing — though a missing row and a registered-but-not-in-HTML row behave identically in a browser, which blunts the consequence.

Why is it free?

Both datasets travel with the page as a few kilobytes, and the check runs in your own browser. Nothing you paste is uploaded, nothing is logged, and there is no account to create.

No sign-up, no limits, and no watermark on anything you copy.