Well-Known URIs

The /.well-known/ path prefix is a standardised place to publish site-level metadata. RFC 8615 defines it; IANA keeps the registry of allowed names.

A standard redirect endpoint that points password managers and users at your real change-password page. Only applicable if the site has user accounts - sites without logins have nothing to point at and should not implement it.

A JSON document at /.well-known/webauthn lists the origins allowed to use passkeys scoped to a single Relying Party ID. It enables WebAuthn Related Origin Requests - one passkey shared across several domains you own. Only applicable if the site uses passkeys across more than one origin.

A JSON discovery document that describes an OpenID Connect provider's endpoints and capabilities. Only required if you are an OIDC identity provider.

A JSON metadata document describing a plain OAuth 2.0 authorisation server's endpoints and capabilities. The non-OIDC sibling of openid-configuration; only needed if you run an authorisation server.

A JSON metadata document that tells clients which authorisation server issues the tokens an OAuth-protected API accepts, and how to present them. Only needed if you expose an OAuth-protected resource.

RFC 9727 publishes a machine-readable index of the APIs and resources a host exposes. Served as a Linkset (RFC 9264) JSON document, discoverable via the api-catalog link relation.

WebFinger (RFC 7033) resolves an account identifier such as acct:user@example.com to a set of links. The Fediverse uses it to discover ActivityPub actors.

A JSON file that tells iOS, iPadOS and macOS which Apple apps may handle which URLs on your domain. Required for Universal Links and several other Apple features.

Android's Digital Asset Links file proves that an Android app and a web domain are owned by the same entity. It powers App Links and Smart Lock for Passwords.

A discovery URI for federated platforms. It returns links to NodeInfo documents that describe the software, version and basic statistics of a server.

A JSON file that tells private prefetch proxies - most notably Chrome's - whether to send prefetch traffic to your origin, and at what fraction. Optional opt-out / throttle mechanism, provisionally registered with IANA.