A well-known URI (RFC 8615) is a fixed path under /.well-known/ where a site publishes something a client needs before it can do anything else — keys, OAuth endpoints, an API catalog, an agent card. IANA keeps the registry. Registration is optional, so it is not the whole picture.
118 paths: 63 permanent and 38 provisional IANA registrations, 5 deprecated or obsoleted, and 12 in use but never registered. 14 are mentioned in a catalog entry. Registry read 2026-10-13 from IANA.
API 25
| Path | Status | Defined by | Registered | Mentioned in |
|---|---|---|---|---|
/.well-known/api-catalog |
permanent | [RFC 9727] | 2024-12-23 | protected-resource-metadata, well-known-uris |
/.well-known/apis.json |
unregistered | APIs.json Machine-readable index of a domain's APIs; served at /apis.json or /.well-known/apis.json. |
||
/.well-known/caldav |
permanent | [RFC 6764] | ||
/.well-known/carddav |
permanent | [RFC 6764] | ||
/.well-known/core |
permanent | [RFC 6690] | coap | |
/.well-known/csvm |
permanent | [https://www.w3.org/TR/tabular-data-model/#default-locations-and-si... | 2015-09-28 | |
/.well-known/genid |
permanent | [RDF 1.1 Concepts and Abstract Syntax] | 2012-11-15 | |
/.well-known/gs1resolver |
permanent | [GS1 Digital Link, Section 7.11] | 2020-05-18 | |
/.well-known/host-meta |
permanent | [RFC 6415] | ||
/.well-known/host-meta.json |
permanent | [RFC 6415] | ||
/.well-known/jmap |
permanent | [RFC8620, Section 2.2] | 2019-03-28 | |
/.well-known/matrix |
permanent | [https://spec.matrix.org/latest/client-server-api/#well-known-uri][... | 2019-04-16 | |
/.well-known/nodeinfo |
provisional | [https://nodeinfo.diaspora.software/] | 2024-07-29 | |
/.well-known/open-resource-discovery |
provisional | [https://sap.github.io/open-resource-discovery/] | 2023-11-27 | open-resource-discovery |
/.well-known/openbindings |
provisional | [https://openbindings.com/spec] | 2026-05-13 | |
/.well-known/openorg |
permanent | [http://opd.data.ac.uk/] | 2015-05-29 | |
/.well-known/oslc |
permanent | [https://docs.oasis-open-projects.org/oslc-op/core/v3.0/ps01/oslc-c... | 2020-12-29 | |
/.well-known/rd |
permanent | [RFC 9176] | 2021-05-04 | |
/.well-known/resourcesync |
permanent | [http://www.openarchives.org/rs/resourcesync] | 2017-05-26 | |
/.well-known/terraform.json |
provisional | [https://developer.hashicorp.com/terraform/internals/remote-service... | 2024-07-01 | |
/.well-known/timezone |
permanent | [RFC 7808] | 2015-08-03 | |
/.well-known/void |
permanent | [http://www.w3.org/TR/void] | 2011-05-11 | |
/.well-known/webfinger |
permanent | [RFC 7033] | 2013-03-15 | webfinger |
/.well-known/wot |
permanent | [https://www.w3.org/TR/wot-discovery/#introduction-well-known] | 2023-01-24 | |
/.well-known/xregistry |
provisional | [https://xregistry.io/xreg/xregistryspecs/core-v1/docs/spec.html] | 2026-08-19 |
Agents & AI 11
| Path | Status | Defined by | Registered | Mentioned in |
|---|---|---|---|---|
/.well-known/agent-card.json |
permanent | [https://a2a-protocol.org/latest/specification/] | 2025-08-01 | protected-resource-metadata |
/.well-known/agent.json |
unregistered | A2A Agent Card (earlier name) Pre-registration A2A path, superseded by the registered agent-card.json; still probed because it is still served. |
||
/.well-known/ai-catalog.json |
unregistered | AI Catalog Domain-level catalog of AI artifacts; MCP Server Cards (SEP-2127) and Agentic Resource Discovery point to it. |
agentic-resource-discovery, ai-agent-auth, ai-catalog, personal-agent-protocol | |
/.well-known/ai-plugin.json |
unregistered | ChatGPT plugin manifest Retired with ChatGPT plugins; still found on the web. |
||
/.well-known/bluejetty |
provisional | [https://bluejettyai.com/standards/iana-well-known/bluejetty] | 2026-09-16 | |
/.well-known/mcp.json |
unregistered | MCP discovery (earlier proposals) Proposed before MCP Server Cards delegated domain discovery to the AI Catalog; never standardized. |
||
/.well-known/ojobpub.json |
provisional | [https://docs.letsemploy.org] | 2026-05-12 | |
/.well-known/poppy.json |
unregistered | Personal Agent Protocol Draft 0.1 (October 2026); a company MUST publish it. |
personal-agent-protocol | |
/.well-known/tdmrep.json |
provisional | [https://www.w3.org/2022/tdmrep/] | 2024-02-15 | |
/.well-known/ucp |
unregistered | Universal Commerce Protocol Agentic commerce profile discovery. |
||
/.well-known/vacation-rental.json |
provisional | [https://vacationrentalprotocol.com/spec/well-known-uri-v0.1] | 2026-08-19 |
OAuth 20
| Path | Status | Defined by | Registered | Mentioned in |
|---|---|---|---|---|
/.well-known/change-password |
provisional | [https://w3c.github.io/webappsec-change-password-url/#the-change-pa... | 2023-03-13 | |
/.well-known/did-configuration.json |
provisional | [https://identity.foundation/.well-known/resources/did-configuration] | 2023-01-31 | |
/.well-known/did.json |
provisional | [https://w3c-ccg.github.io/did-method-web] | 2023-01-31 | |
/.well-known/gnap-as-rs |
permanent | [RFC9767, Section 3.1] | 2024-10-23 | |
/.well-known/hoba |
permanent | [RFC7486, Section 6] | 2015-01-20 | |
/.well-known/http-message-signatures-directory |
unregistered | Web Bot Auth key directory IETF draft; where a bot or agent publishes the keys it signs requests with. |
||
/.well-known/idp-proxy |
permanent | [RFC 8827] | 2019-07-25 | |
/.well-known/jwks.json |
unregistered | JSON Web Key Set (convention) A convention, not a registration — the normative pointer is jwks_uri in OAuth/OpenID metadata. |
jwk | |
/.well-known/keybase.txt |
permanent | [https://keybase.io/__/keybase_well_known] | 2014-04-08 | |
/.well-known/nfv-oauth-server-configuration |
permanent | [ETSI GS NFV-SEC 022 V2.7.1] | 2019-06-26 | |
/.well-known/nostr.json |
provisional | [https://github.com/nostr-protocol/nips/blob/master/05.md] | 2024-03-18 | |
/.well-known/oauth-authorization-server |
permanent | [RFC8414, Section 3] | 2018-03-27 | protected-resource-metadata |
/.well-known/oauth-protected-resource |
permanent | [RFC9728, Section 3] | 2024-10-22 | protected-resource-metadata |
/.well-known/openid-configuration |
permanent | [http://openid.net/specs/openid-connect-discovery-1_0.html] | 2013-08-27 | protected-resource-metadata |
/.well-known/openid-federation |
provisional | [Section 9 of OpenID Federation 1.0] | 2024-07-26 | |
/.well-known/private-token-issuer-directory |
permanent | [RFC 9578] | 2023-10-09 | |
/.well-known/smart-configuration |
unregistered | SMART App Launch configuration SMART on FHIR authorization discovery, relative to the FHIR base URL. |
smart-on-fhir | |
/.well-known/ssf-configuration |
provisional | [https://openid.net/specs/openid-sharedsignals-framework-1_0-ID2.html] | 2024-04-18 | |
/.well-known/uma2-configuration |
permanent | [UMA 2.0 Grant for OAuth 2.0, Section 2] | 2017-06-20 | |
/.well-known/webauthn |
permanent | [https://www.w3.org/TR/webauthn-3/#well-known-uri-registration] | 2026-01-23 |
Security 18
| Path | Status | Defined by | Registered | Mentioned in |
|---|---|---|---|---|
/.well-known/acme-challenge |
permanent | [RFC8555, Section 8.3] | 2016-08-18 | |
/.well-known/brski |
permanent | [RFC 8995] | 2020-10-09 | |
/.well-known/cmp |
permanent | [RFC 9811][RFC 9482] | 2021-05-20 | |
/.well-known/csaf |
provisional | [Common Security Advisory Framework Version 2.0, OASIS Standard] | 2023-02-10 | |
/.well-known/csaf-aggregator |
provisional | [Common Security Advisory Framework Version 2.0, OASIS Standard] | 2023-02-10 | |
/.well-known/dots |
permanent | [RFC 9132] | 2020-01-16 | |
/.well-known/enterprise-network-security |
permanent | [ETSI TS 103 523-5 clause 4.3.4.3.4.2] | 2022-02-07 | |
/.well-known/enterprise-transport-security |
permanent | [ETSI TS 103 523-3 clause 4.3.8.3] | 2019-05-14 | |
/.well-known/est |
permanent | [RFC 7030][RFC 9148] | 2013-08-16 | |
/.well-known/mta-sts.txt |
permanent | [RFC 8461] | 2018-06-21 | |
/.well-known/pki-validation |
permanent | [Section 3.2.2.4.6 of version 1.3.8 of the CA/Browser Forum’s Basel... | 2017-02-06 | |
/.well-known/sbom |
permanent | [RFC 9472] | 2023-05-12 | |
/.well-known/scitt-keys |
permanent | [RFC-ietf-scitt-scrapi-11] | 2026-07-01 | |
/.well-known/security.txt |
permanent | [RFC 9116] | 2021-07-13 | security-txt |
/.well-known/ssh-known-hosts |
provisional | [https://c2sp.org/well-known-ssh-hosts] | 2025-12-16 | |
/.well-known/sshfp |
provisional | [https://sshfp.github.io/sshfp.html] | 2020-07-21 | |
/.well-known/tea |
provisional | [Transparency Exchange API (coming)] | 2026-02-28 | |
/.well-known/webhook-authorized-senders.json |
permanent | [https://intempus.dk/webhook-authorization] | 2025-09-29 |
Data spaces 1
| Path | Status | Defined by | Registered | Mentioned in |
|---|---|---|---|---|
/.well-known/dspace-version |
unregistered | Dataspace Protocol version metadata Required by the Dataspace Protocol 2025-1 ("MUST provide"). |
dataspace-protocol |
Web 16
| Path | Status | Defined by | Registered | Mentioned in |
|---|---|---|---|---|
/.well-known/amphtml |
provisional | [https://developers.google.com/amp/cache/update-cache] | 2020-07-06 | |
/.well-known/apple-app-site-association |
unregistered | Apple universal links Associates a domain with iOS and macOS apps. |
||
/.well-known/appspecific |
provisional | [https://github.com/Vroo/well-known-uri-appspecific/blob/main/well-... | 2021-06-01 | |
/.well-known/assetlinks.json |
permanent | [https://github.com/google/digitalassetlinks/blob/master/well-known... | 2015-09-28 | |
/.well-known/dnt |
permanent | [http://www.w3.org/TR/tracking-dnt/#status-resource] | 2015-08-19 | |
/.well-known/dnt-policy.txt |
permanent | [https://www.eff.org/dnt-policy] | 2015-08-19 | |
/.well-known/funding-manifest-urls |
provisional | [https://fundingjson.org/] | 2025-04-02 | |
/.well-known/gpc.json |
provisional | [Global Privacy Control (GPC)] | 2022-01-28 | |
/.well-known/hosting-provider |
provisional | [https://github.com/Automattic/hosting-provider] | 2020-07-21 | |
/.well-known/ic-domains |
provisional | [https://docs.internetcomputer.org/building-apps/frontends/custom-d... | 2026-01-12 | |
/.well-known/privacy-sandbox-attestations.json |
deprecated | [https://github.com/privacysandbox/attestation] | 2024-12-04 | |
/.well-known/related-website-set.json |
deprecated | [https://github.com/GoogleChrome/related-website-sets/blob/main/Wel... | 2023-12-01 | |
/.well-known/tpcd |
deprecated | [The "tpcd/grace-period.json" Well-Known Resource Identifier] | 2024-05-08 | |
/.well-known/traffic-advice |
provisional | [https://buettner.github.io/private-prefetch-proxy/traffic-advice.h... | 2022-03-29 | |
/.well-known/trust.txt |
provisional | [https://journallist.net/reference-document-for-trust-txt-specifica... | 2022-02-04 | |
/.well-known/webweaver.json |
provisional | [https://www.webweaver.de/well-known] | 2022-08-11 |
Network 27
| Path | Status | Defined by | Registered | Mentioned in |
|---|---|---|---|---|
/.well-known/ashrae |
permanent | [http://www.bacnet.org/Addenda/Add-135-2012am-ppr3-draft-17_chair_a... | 2016-01-22 | |
/.well-known/broadband-labels |
provisional | [https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5681704] | 2024-08-30 | |
/.well-known/cdmi |
provisional | [https://www.snia.org/sites/default/files/technical-work/cdmi/Publi... | 2026-10-07 | |
/.well-known/coap |
permanent | [RFC 8323] | 2017-12-22 | |
/.well-known/coap-eap |
permanent | [RFC 9820] | 2025-02-14 | |
/.well-known/csipaus |
provisional | [SA TS 5573:2025 Common Smart Inverter Profile - Australia with Tes... | 2026-07-31 | |
/.well-known/cyclic-trigger |
provisional | [https://github.com/SmartStandards/.well-known.cyclic-trigger] | 2026-08-17 | |
/.well-known/easy-proxy |
provisional | [https://github.com/bytedance/g3/blob/master/doc/easy-proxy.md] | 2025-05-01 | |
/.well-known/ecips |
provisional | [https://ecips.that.world/24-ECIPURI] | 2019-04-10 | |
/.well-known/edhoc |
permanent | [RFC 9528] | 2023-08-29 | |
/.well-known/http-opportunistic |
obsoleted | [RFC8164, Section 2.3][Status change of HTTP experiments to Historic] | 2017-03-20 | |
/.well-known/knx |
provisional | [https://knxcloud.org/index.php/s/jdZXpCC3EolQgH2/download] | 2023-08-15 | |
/.well-known/looking-glass |
permanent | [RFC8522, Section 2] | 2018-12-07 | |
/.well-known/masque |
permanent | [RFC 9298][RFC 9484] | 2022-06-23 | |
/.well-known/mercure |
provisional | [https://mercure.rocks/spec] | 2023-03-20 | |
/.well-known/mud |
obsoleted | 2016-11-23 | ||
/.well-known/ni |
permanent | [RFC 6920] | ||
/.well-known/ohttp-gateway |
permanent | [RFC 9540] | 2023-10-25 | |
/.well-known/posh |
permanent | [RFC 7711] | 2015-09-20 | |
/.well-known/probing.txt |
permanent | [RFC 9511] | 2023-09-01 | |
/.well-known/pvd |
permanent | [RFC 8801] | 2020-02-18 | |
/.well-known/reload-config |
permanent | [RFC 6940] | ||
/.well-known/repute-template |
permanent | [RFC 7072] | 2013-09-30 | |
/.well-known/stun-key |
permanent | [RFC 7635] | 2015-06-12 | |
/.well-known/thread |
permanent | [https://www.threadgroup.org/support#specifications] | 2018-11-29 | |
/.well-known/time |
permanent | [http://phk.freebsd.dk/time/20151129/] | 2015-12-09 | |
/.well-known/tor-relay |
provisional | [The "tor-relay" Well-Known Resource Identifier] | 2020-10-06 |
Built by PLANNING/build-well-known.py from the live IANA CSV and PLANNING/well-known-unregistered.yml. Unregistered paths are listed only when a published specification or documented convention defines them.