A well-known URI is a Uniform Resource Identifier for URL path prefixes that start with /.well-known/. They are implemented in webservers so that requests to the servers for well-known services or information are available at URL consistent well-known locations across servers.
Description
Well-known URIs are Uniform Resource Identifiers defined by the IETF in RFC 8615. They are URL path prefixes that start with /.well-known/. This implementation is in response to the common expectation for web-based protocols to require certain services or information be available at URLs consistent across servers, regardless of the way URL paths are organized on a particular host. The URIs are implemented in webservers so that requests to the servers for well-known services or information are available at URLs consistently in well-known locations across servers.
The IETF has defined a simple way for web servers to hold metadata that any user agent (e.g., web browser) can request. The metadata is useful for various tasks, including directing a web user to use a mobile app instead of the website or indicating the different ways that the site can be secured. The well-known locations are used by web servers to share metadata with user agents; sometimes these are files and sometimes these are requests for information from the web server software itself. The way to declare the different metadata requests that can be provided is standardized by the IETF so that other developers know how to find and use this information.
Use The path well-known URI begins with the characters /.well-known/, and whose scheme is "HTTP", "HTTPS", or another scheme that has explicitly been specified to use well-known URIs. As an example, if an application hosts the service "example", the corresponding well-known URIs on https://www.example.com/ would start with https://www.example.com/.well-known/example.
Information shared by a web site as a well-known service is expected to meet a specific standard. Specifications that need to define a resource for such site-wide metadata can register their use with the Internet Assigned Numbers Authority (IANA) to avoid collisions and minimize impingement upon sites' URI space.
List of well-known URIs The list below describes known standards for .well-known services that a web server can implement. URI suffix Description Reference Date of IANA registrationacme-challengeAutomated Certificate Management Environment (ACME)2019-03-01agent-card.jsonDetails for an A2A Server's Agent Cardai-catalog.jsonAgentic Resource Discovery Specificationai-plugin.jsonManifest for a ChatGPT pluginapple-app-site-associationAn Apple service that enables secure data exchange between iOS and a websiteapple-developer-merchantid-domain-associationApple PayappspecificUsed by some application to get some informations about the application (e.g. chrome devtools: appspecific/com.chrome.devtools.json)ashraeBACnetA data communication protocol for building automation and control networks2016-01-22assetlinks.jsonAssetLinks protocol used to identify one or more digital assets (such as web sites or mobile apps) that are related to the hosting web site in some fashion2015-09-28atproto-didHandle-to-DID resolution for AT Protocolautoconfig/mailMozilla Thunderbird mail autoconfiguration servicebrowseridMozilla PersonacaldavCalendaring Extensions to WebDAV (CalDAV) and vCard Extensions to WebDAV (CardDAV)carddavCalendaring Extensions to WebDAV (CalDAV) and vCard Extensions to WebDAV (CardDAV)change-passwordHelps password managers find the URL for changing client account passwordscoapCoAP (Constrained Application Protocol) over TCP, TLS, and WebSockets2017-12-22com.apple.remotemanagementApple-Account–based user enrollment for mobile device managementcom.chrome.devtools.jsonAutomatic Workspace Folders - Chromium DevTools Ecosystem Guide for Web development tools coreConstrained RESTful Environments (CoRE) Link FormatcsvmCSV metadata, Model for Tabular Data and Metadata on the Web2015-09-28datLinks domain to Dat identifier, used by Beaker web browserdid.jsondid:web Decentralized Identifiers (DIDs) for the WebdiscordDomain verification for Discord account connectiondntSite-wide tracking status resource2015-08-19dnt-policy.txtA privacy-friendly Do Not Track (DNT) Policy2015-08-19estEnrollment over Secure Transport (EST)2013-08-16genidResource Description Framework (RDF) Skolem IRIs2012-11-15gpc.jsonGlobal Privacy Control (GPC)hobaHTTP Origin-Bound Authentication (HOBA)2015-01-20host-metaWeb Host Metadatahost-meta.jsonWeb Host Metadatahttp-opportunisticOpportunistic Security for HTTP/22017-03-20keybase.txtUsed by the Keybase project to identify a proof that one or more people whose public keys may be retrieved using the Keybase service have administrative control over the origin server from which it is retrieved2014-04-08keyparcUsed by the Bloombase Keyparc project to secure online digital assets using cryptography over web services2012-09-23matrixProvides discovery for both client and server APIs to the Matrix federated protocolmercureDiscovery of Mercure hubs. Mercure is a protocol enabling the pushing of data updates to web browsers and other HTTP clients in a fast, reliable and battery-efficient way.mta-sts.txtSMTP MTA Strict Transport Security Policy2018-06-21niNaming Things with HashesnodeinfoMetadata for federated social networking serversnostr.jsonDiscovery of Nostr public keys and related relays, according to NIP-052024-03-18oauth-authorization-serverOAuth Authorization Server Metadata2018-03-27openid-configurationOpenID Connect2013-08-27openorgOrganisation Profile Document2015-05-29openpgpkeyOpenPGP Web Key Serviceorg.flathub.VerifiedApps.txtVerifies that an app is associated with given domain in Flathubpasskey-endpointsFormally advertises support for passkeys and provides direct links for enrollment and management for password managers to automatically create/upgrade.pki-validationCA/Browser Forum's Baseline Requirements Certificate Policy for the Issuance and Management of Publicly-Trusted Certificates2017-02-06poshPKIX over Secure HTTP (POSH)2015-09-20privacy-sandbox-attestations.jsonThe Google Chrome Privacy Sandbox attestation filepubvendors.jsonThe IAB pubvendors.json tech spec, which provide a standard for publishers to publicly declare the vendors that they work with, and their respective data rights/configuration2020-09-07reload-configREsource LOcation And Discovery (RELOAD) Base Protocolrepute-templateA Reputation Query Protocol2013-09-30resourcesyncResourceSync Framework Specification2017-05-26security.txtStandard to help organizations define the process for security researchers to disclose security vulnerabilities2018-08-20smart-configurationSMART on FHIR configuration metadata, including OAuth authorization_endpoint and token_endpoint URLs2023-03-01statements.txtStandard for collective contract signingstun-keySession Traversal Utilities for NAT (STUN) Extension for Third-Party Authorization2015-06-12tdmrep.jsonDomain-wide TDM (Text and Data Mining) reservationtimeTime over HTTPS specification2015-12-09timezoneTime Zone Data Distribution Service2015-08-03traffic-advicePrefetch control (proposal; implemented in Chrome Privacy Preserving Prefetch Proxy crawler)ucpBusiness profile declaring supported capabilities for the Universal Commerce Protocol (UCP)uma2-configurationUser-Managed Access (UMA) 2.0 grant for OAuth 2.0 authorization2017-06-20vercel/flagsOverridable Feature Flag's for Vercel's ToolbarvoidDescribing Linked Datasets with the VoID Vocabulary2011-05-11wasm-pkg/registry.jsonWebAssembly registrywebauthnWebAuthn Related OriginswebfingerWebFinger2013-03-15, 2013-09-06workflowWorkflow Development Kit Routesxrp-ledger.tomlXRP ledger node & account information
References
Footnotes
External links Well-Known URIs registry at Internet Assigned Numbers Authority