RFC 9701

JSON Web Token (JWT) Response for OAuth Token Introspection

📅 published January 2025, from ietf

📜 RFC 9701: JSON Web Token (JWT) Response for OAuth Token Introspection 🎀

okay bestie, this one is SO my vibe 💅 It's a Standards Track doc from January 2025, written by T. Lodderstedt (yes.com AG) and V. Dzhuvinov (Connect2id Ltd.) 🫶 It's an IETF product, published as RFC 9701, ISSN 2070-1721. It doesn't obsolete or update anything, so it's a fresh new thing. ✨

The whole point: normal OAuth token introspection responses are just plain JSON 📄, but some apps need stronger proof that the authorization server really issued the response 🔐. This spec lets the introspection endpoint hand back a signed JWT instead. Main character energy 👑

Below is part 1 of 3 (the title block, the Status and Copyright stuff, the table of contents, and Sections 1 through 4). More parts coming, so stay tuned 🦋

Abstract 🌸

This spec proposes an additional response secured by JSON Web Token (JWT) for OAuth 2.0 Token Introspection. 💖

Status of This Memo ✨

This is an Internet Standards Track document. 🌈

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.

Info about the current status of this doc, any errata, and how to give feedback can be found at https://www.rfc-editor.org/info/rfc9701 🔗 (no links in this terminal, so copy-paste it if you want it 🙈)

Copyright Notice 🎀

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, since they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. ⚖️

Table of Contents 🧚

1.  Introduction
2.  Requirements Notation
3.  Resource Server Management
4.  Requesting a JWT Response
5.  JWT Response
6.  Client Metadata
7.  Authorization Server Metadata
8.  Security Considerations
  8.1.  Cross-JWT Confusion
  8.2.  Token Data Leakage
9.  Privacy Considerations
10. IANA Considerations
  10.1.  OAuth Dynamic Client Registration Metadata Registration
    10.1.1.  Registry Contents
  10.2.  OAuth Authorization Server Metadata Registration
    10.2.1.  Registry Contents
  10.3.  Media Type Registration
    10.3.1.  Registry Contents
  10.4.  JWT Claim Registration
    10.4.1.  Registry Contents
11. References
  11.1.  Normative References
  11.2.  Informative References
Acknowledgements
Authors' Addresses

1. Introduction 🦋

So, "OAuth 2.0 Token Introspection" [RFC7662] is the spec that lets a protected resource ask an OAuth 2.0 authorization server "hey, is this access token still good, and what's its deal?" 🕵️‍♀️ It also gets back the data tied to that token. This is what lets deployments use opaque access tokens in an interoperable way. Iconic 💅

Here's the thing: the introspection response in RFC 7662 is just a plain JSON object 📄. But some use cases need the resource server to have stronger assurance that the authorization server actually issued that introspection response for the access token 🔐. This includes cases where the authorization server takes on liability for what's in the response. Example: a resource server using verified personal data to make certificates, which then get used to make qualified electronic signatures ✍️ (serious stakes, bestie 😭).

In those situations, it may be useful or even required to return a signed JWT [RFC7519] as the introspection response 🎀. So this spec extends the token introspection endpoint so it can return responses as JWTs. Slay 💖

2. Requirements Notation 🌸

Okay, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be read as described in BCP 14 [RFC2119] [RFC8174], but ONLY when they show up in all capitals, exactly like this 🔤. Lowercase ones are just regular words, no cap 🙅‍♀️.

3. Resource Server Management 👑

The authorization server (AS) and the resource server (RS) have a strong, two-way trust relationship 🤝. The resource server relies on the authorization server to get authorization, user data, and other data it uses for access control decisions and service delivery. The authorization server relies on the resource server to handle that data appropriately 💅.

In this spec, the token introspection endpoint is used to pass along security data, and possibly privacy-sensitive data about an access token 🔒.

To process introspection requests in a secure and privacy-preserving way, the authorization server MUST be able to identify, authenticate, and authorize resource servers. This is non-negotiable, bestie 🙅‍♀️.

The AS MAY also encrypt the token introspection response JWTs 🔐. If it does, the AS is provisioned with encryption keys and algorithms for the RS 🗝️.

The AS MUST be able to determine whether an RS is the audience for a particular access token, and what data it's entitled to receive. Otherwise the RS is NOT authorized to get data for that access token 🚫. How the AS handles this is up to it 🤷‍♀️. For example, it could keep a mapping between scope values and RSs 🗺️.

The requirements above mean the AS keeps credentials and other config data for each RS 📋.

One way to do this is dynamic client registration [RFC7591], where every RS is treated as an OAuth client 🧑‍💻. In that case, the AS is assumed to at least maintain a "client_id" and a "token_endpoint_auth_method" with matching authentication method metadata, like "jwks" or "client_secret" 🔑. When the AS needs to get consent before sending data to an RS, the following client metadata fields are RECOMMENDED: "client_name", "client_uri", "contacts", "tos_uri", and "policy_uri" 💖.

The AS MUST restrict the use of client credentials by an RS to the calls it needs. For example, the AS MAY restrict such a client to only calling the token introspection endpoint 🔐. How the AS implements that restriction is out of scope for this spec 🙈.

This spec also introduces client metadata to manage the config options needed to sign and encrypt token introspection response JWTs ✨.

4. Requesting a JWT Response 🧚

An RS asks for a JWT introspection response by sending an introspection request with an Accept HTTP header field set to application/token-introspection+jwt 🎯.

The AS MUST authenticate the caller at the token introspection endpoint. Authentication can use client authentication methods, or a separate access token that's issued to the RS and identifies the RS as the subject 🪪.

Here's a non-normative example request, where the RS authenticates with a private key JWT (it's just an example, so don't treat it as the rule 🙈):

POST /introspect HTTP/1.1
Host: as.example.com
Accept: application/token-introspection+jwt
Content-Type: application/x-www-form-urlencoded

token=2YotnFZFEjr1zCsicMWpAA&
client_assertion_type=
 urn%3Aietf%3Aparams%3Aoauth%3Aclient-assertion-type%3Ajwt-bearer&
 client_assertion=PHNhbWxwOl[...omitted for brevity...]ZT

That's part 1 done, bestie 🦋 Part 2 is coming next with Section 5 (JWT Response) and Section 6 (Client Metadata) 💜

5. JWT Response 💌

okay so the introspection endpoint answers with a JWT 🎀 It sets the Content-Type HTTP header field to application/token-introspection+jwt, and the JWT typ ("type") header parameter gets token-introspection+jwt. ✨

The JWT MUST include these top-level claims:

iss: MUST be set to the issuer URL of the authorization server 🏛️
aud: MUST identify the resource server receiving the token introspection response 🎯
iat: MUST be set to the time when the introspection response was created by the authorization server ⏰
token_introspection: a JSON object holding the members of the token introspection response, as specified in [RFC7662], Section 2.2. Putting the introspection members in their own JSON object, as a JWT claim, is a smart move 🧠 It stops them from clashing or getting confused with top-level JWT claims that happen to share a name 💅

If the access token is invalid, expired, revoked, or not intended for the calling resource server (audience), the authorization server MUST set the value of the active member in the token_introspection claim to false and MUST NOT include other members. Otherwise, the active member is set to true. 🚫

The AS SHOULD narrow down the scope value to the scopes relevant to the particular RS. 🎯

As specified in Section 2.2 of [RFC7662], implementations MAY extend the token introspection response with service-specific claims. In this specification, those claims get added as top-level members of the token_introspection claim 🧩

Token introspection response parameter names that are meant to be used across domains MUST be registered in the "OAuth Token Introspection Response" registry [IANA.OAuth.Token.Introspection], which is defined by [RFC7662]. 📒

When the AS acts as a provider of resource owner identity claims to the RS, the AS decides, based on its RS-specific policy, which identity claims go back in the token introspection response. The AS MUST ensure the release of any privacy-sensitive data is legally based (see Section 9). 🔐 Privacy is everything, bestie 🥹

Any further content of the introspection response is determined by the RS-specific policy at the AS. 📋

The JWT MAY include other claims, including those from the "JSON Web Token Claims" registry established by [RFC7519]. The JWT SHOULD NOT include the sub and exp claims, as an extra layer of protection against misuse of the JWT as an access token (see Section 8.1). 🛡️

Note: Yes, the JWT format is super popular as an access token format, but the JWT returned in the introspection response is NOT an alternative representation of the introspected access token. It is not meant to be used as an access token. Don't mix them up 🙅‍♀️

This specification registers the application/token-introspection+jwt media type. It goes in the typ ("type") header parameter of the JWT to show that the payload is a token introspection response 🦋

The JWT is cryptographically secured as specified in [RFC7519]. 🔒

Depending on the specific resource server policy, the JWT is either signed, or signed and encrypted. If the JWT is signed and encrypted, it MUST be a Nested JWT, as defined in JWT [RFC7519]. 🪆

Note: An AS compliant with this specification MUST refuse to serve introspection requests that don't authenticate the caller, and it MUST return an HTTP status code 400. This keeps token data going only to legit recipients and stops anyone from downgrading to [RFC7662] behavior (see Section 8.2). Absolutely no sneaky downgrades 😤

The following is a non-normative example response (with line breaks for display purposes only) 🌸

HTTP/1.1 200 OK
Content-Type: application/token-introspection+jwt

eyJraWQiOiJ3RzZEIiwidHlwIjoidG9rZW4taW50cm9zcGVjdGlvbitqd3QiLCJhbGc
iOiJSUzI1NiJ9.eyJpc3MiOiJodHRwczovL2FzLmV4YW1wbGUuY29tLyIsImF1ZCI6I
mh0dHBzOi8vcnMuZXhhbXBsZS5jb20vcmVzb3VyY2UiLCJpYXQiOjE1MTQ3OTc4OTIs
InRva2VuX2ludHJvc3BlY3Rpb24iOnsiYWN0aXZlIjp0cnVlLCJpc3MiOiJodHRwczo
vL2FzLmV4YW1wbGUuY29tLyIsImF1ZCI6Imh0dHBzOi8vcnMuZXhhbXBsZS5jb20vcm
Vzb3VyY2UiLCJpYXQiOjE1MTQ3OTc4MjIsImV4cCI6MTUxNDc5Nzk0MiwiY2xpZW50X
2lkIjoicGFpQjJnb28wYSIsInNjb3BlIjoicmVhZCB3cml0ZSBkb2xwaGluIiwic3Vi
IjoiWjVPM3VwUEM4OFFyQWp4MDBkaXMiLCJiaXJ0aGRhdGUiOiIxOTgyLTAyLTAxIiw
iZ2l2ZW5fbmFtZSI6IkpvaG4iLCJmYW1pbHlfbmFtZSI6IkRvZSIsImp0aSI6InQxRm
9DQ2FaZDRYdjRPUkpVV1ZVZVRaZnNLaFczMENRQ3JXRERqd1h5NncifX0.przJMU5Gh
mNzvwtt1Sr-xa9xTkpiAg5IshbQsRiRVP_7eGR1GHYrNwQh84kxOkHCyje2g5WSRcYo
sGEVIiC-eoPJJ-qBwqwSlgx9JEeCDw2W5DjrblOI_N0Jvsq_dUeOyoWVMqlOydOBhKN
Y0smBrI4NZvEExucOm9WUJXMuJtvq1gBes-0go5j4TEv9sOP9uu81gqWTr_LOo6pgT0
tFFyZfWC4kbXPXiQ2YT6mxCiQRRNM-l9cBdF6Jx6IOrsfFhBuYdYQ_mlL19HgDDOFal
eyqmru6lKlASOsaE8dmLSeKcX91FbG79FKN8un24iwIDCbKT9xlUFl54xWVShNDFA

The example response JWT header contains this JSON document 🧾

{
  "typ": "token-introspection+jwt",
  "alg": "RS256",
  "kid": "wG6D"
}

The example response JWT payload contains this JSON document 👀

{
  "iss":"https://as.example.com/",
  "aud":"https://rs.example.com/resource",
  "iat":1514797892,
  "token_introspection":
     {
        "active":true,
        "iss":"https://as.example.com/",
        "aud":"https://rs.example.com/resource",
        "iat":1514797822,
        "exp":1514797942,
        "client_id":"paiB2goo0a",
        "scope":"read write dolphin",
        "sub":"Z5O3upPC88QrAjx00dis",
        "birthdate":"1982-02-01",
        "given_name":"John",
        "family_name":"Doe",
        "jti":"t1FoCCaZd4Xv4ORJUWVUeTZfsKhW30CQCrWDDjwXy6w"
     }
}

6. Client Metadata 🎀

The authorization server decides which algorithm secures the JWT for a particular introspection response. That decision can be based on registered metadata parameters for the resource server. Those get supplied through dynamic client registration [RFC7591], with the resource server acting as a client, as described below 🤝

The parameter names follow the pattern set by OpenID Connect Dynamic Client Registration [OpenID.Registration] for configuring signing and encryption algorithms for JWT responses at the UserInfo endpoint. Copying a good pattern is a power move 💜

This specification introduces the following client metadata parameters:

introspection_signed_response_alg: OPTIONAL. This is the "JSON Web Signature (JWS)" [RFC7515] algorithm (alg value), as defined in "JSON Web Algorithms (JWA)" [RFC7518], used for signing introspection responses. If it's specified, the response is signed using JWS and the configured algorithm. If it's omitted, the default is RS256 ✍️
introspection_encrypted_response_alg: OPTIONAL. This is the "JSON Web Encryption (JWE)" [RFC7516] algorithm (alg value), as defined in JWA [RFC7518], for content key encryption. If it's specified, the response is encrypted using JWE and the configured content encryption algorithm (introspection_encrypted_response_enc). If it's omitted, no encryption happens. If both signing and encryption are requested, the response gets signed and then encrypted, and the result is a Nested JWT, as defined in JWT [RFC7519] 🪆
introspection_encrypted_response_enc: OPTIONAL. This is the JWE [RFC7516] algorithm (enc value), as defined in JWA [RFC7518], for content encryption of introspection responses. If it's omitted, the default is A128CBC-HS256. Note: this parameter MUST NOT be specified without setting introspection_encrypted_response_alg ⚠️

Resource servers are free to register their public encryption keys using the jwks_uri or jwks metadata parameters 🔑

7. Authorization Server Metadata 🏛️

Authorization servers SHOULD publish the supported algorithms for signing and encrypting the JWT of an introspection response, using the "OAuth 2.0 Authorization Server Metadata" [RFC8414] parameters. Resource servers use this data to set up their client registration requests 📣

This specification introduces the following parameters:

introspection_signing_alg_values_supported: OPTIONAL. A JSON array listing the JWS [RFC7515] signing algorithms (alg values), as defined in JWA [RFC7518], that the introspection endpoint supports for signing the response ✍️
introspection_encryption_alg_values_supported: OPTIONAL. A JSON array listing the JWE [RFC7516] encryption algorithms (alg values), as defined in JWA [RFC7518], that the introspection endpoint supports for encrypting the content encryption key for introspection responses (content key encryption) 🔐
introspection_encryption_enc_values_supported: OPTIONAL. A JSON array listing the JWE [RFC7516] encryption algorithms (enc values), as defined in JWA [RFC7518], that the introspection endpoint supports for encrypting the response (content encryption) 🧁

8. Security Considerations 🛡️😭

This part is SERIOUS, bestie, so read it carefully 👑

8.1. Cross-JWT Confusion

The iss claim, and potentially the aud claim, of a token introspection JWT can look a lot like those of a JWT-encoded access token. An attacker could try to exploit that and pass a JWT token introspection response to the resource server as if it were an access token 🕵️‍♀️ The typ ("type") JWT header token-introspection+jwt and the encapsulation of the token introspection members (like sub and scope inside the token_introspection claim) are there to prevent these substitution attacks 🧱 So, resource servers MUST check the typ JWT header value of received JWT-encoded access tokens, and they MUST make sure all minimally required claims for a valid access token are present ✅

Resource servers MUST also apply the countermeasures against access token replay, as described in [RFC9700] 🔁

JWT confusion and other attacks involving JWTs are discussed in [RFC8725] 📚

8.2. Token Data Leakage

The authorization server MUST use Transport Layer Security (TLS) 1.2 (or higher), per BCP 195 [RFC9325], to prevent token data leakage 🔒🚫

Section 2.1 of [RFC7662] permits requests to the introspection endpoint to be authorized with an access token that doesn't identify the caller. To keep tokens from being introspected by parties that aren't the intended consumer, the authorization server MUST require all requests to the token introspection endpoint to be authenticated 🙅‍♀️🔐

9. Privacy Considerations 🔐✨

okay so bestie, this section is SERIOUS but I'm gonna explain it in a way that won't make your brain melt 🫶. The token introspection response can carry personal identifiable information (PII) from the AS over to the RS 😭. So the AS MUST conform to legal and jurisdictional constraints for the data transfer before any data is released to a particular RS 💅. The details and determining of these constraints vary by jurisdiction and are outside the scope of this document 🌍, so this doc isn't gonna tell you the rules, periodt.

A commonly found way to establish the legal basis for releasing PII is explicit user consent gathered from the resource owner by the AS during the authorization flow 🎀. It's giving "may I please" energy.

It's also possible that the legal basis is established out of band 🧚. For example, that could be an explicit contract, or the client gathering the resource owner's consent.

If the AS and the RS belong to the same legal entity (1st party scenario), there is potentially no need for explicit user consent 🌸, but the terms of service and policy of the respective service provider MUST be enforced at all times 👑. No exceptions, no cap.

In any case, the AS MUST ensure that the scope of the legal basis is enforced throughout the whole process 🦋. The AS MUST retain the scope of the legal basis with the access token, e.g., in the scope value, it MUST authenticate the RS, and the AS MUST determine the data an RS is allowed to receive based on the RS's identity and suitable token data, e.g., the scope value 💖. Main character energy for the AS, fr fr.

Implementers should be aware that a token introspection request lets the AS know when the client (and potentially the user) is accessing the RS 👀, which is also an indication of when the user is using the client 🙈. If this implication is not acceptable, implementers MUST use other means to relay access token data, for example, by directly transferring the data needed by the RS within the access token 🍓. Iconic, honestly.

10. IANA Considerations 📋💜

10.1. OAuth Dynamic Client Registration Metadata Registration 🌈

The following client metadata definitions have been registered in the IANA "OAuth Dynamic Client Registration Metadata" registry [IANA.OAuth.Parameters] established by [RFC7591]:

10.1.1. Registry Contents

Client Metadata Name:  introspection_signed_response_alg
Client Metadata Description:  String value indicating the client's
   desired introspection response signing algorithm
Change Controller:  IETF
Reference:  Section 6 of RFC 9701

Client Metadata Name:  introspection_encrypted_response_alg
Client Metadata Description:  String value specifying the desired
   introspection response content key encryption algorithm (alg
   value)
Change Controller:  IETF
Reference:  Section 6 of RFC 9701

Client Metadata Name:  introspection_encrypted_response_enc
Client Metadata Description:  String value specifying the desired
   introspection response content encryption algorithm (enc value)
Change Controller:  IETF
Reference:  Section 6 of RFC 9701

10.2. OAuth Authorization Server Metadata Registration 🎀

The following values have been registered in the IANA "OAuth Authorization Server Metadata" registry [IANA.OAuth.Parameters] established by [RFC8414].

10.2.1. Registry Contents

Metadata Name:  introspection_signing_alg_values_supported
Metadata Description:  JSON array containing a list of algorithms
   supported by the authorization server for introspection response
   signing
Change Controller:  IETF
Reference:  Section 7 of RFC 9701

Metadata Name:  introspection_encryption_alg_values_supported
Metadata Description:  JSON array containing a list of algorithms
   supported by the authorization server for introspection response
   content key encryption (alg value)
Change Controller:  IETF
Reference:  Section 7 of RFC 9701

Metadata Name:  introspection_encryption_enc_values_supported
Metadata Description:  JSON array containing a list of algorithms
   supported by the authorization server for introspection response
   content encryption (enc value)
Change Controller:  IETF
Reference:  Section 7 of RFC 9701

10.3. Media Type Registration 🦋

The application/token-introspection+jwt media type has been registered in the "Media Types" registry [IANA.MediaTypes] in the manner described in [RFC6838]. It can be used to indicate that the content is a token introspection response in JWT format 💅.

10.3.1. Registry Contents

Type name:  application

Subtype name:  token-introspection+jwt

Required parameters:  N/A

Optional parameters:  N/A

Encoding considerations:  binary.  A token introspection response is
   a JWT; JWT values are encoded as a series of base64url-encoded
   values (with trailing '=' characters removed), some of which may
   be the empty string, separated by period ('.') characters.

Security considerations:  See Section 8 of RFC 9701

Interoperability considerations:  N/A

Published specification:  Section 4 of RFC 9701

Applications that use this media type:  Applications that produce and
   consume OAuth Token Introspection Responses in JWT format

Fragment identifier considerations:  N/A

Additional information:
   Magic number(s):  N/A
   File extension(s):  N/A
   Macintosh file type code(s):  N/A

Person & email address to contact for further information:
   Torsten Lodderstedt (torsten@lodderstedt.net)

Intended usage:  COMMON

Restrictions on usage:  none

Author:  Torsten Lodderstedt (torsten@lodderstedt.net)

Change controller:  IETF

10.4. JWT Claim Registration 🧚

The "token_introspection" claim has been registered in the "JSON Web Token (JWT)" registry [IANA.JWT] in the manner described in [RFC7519] 💜.

10.4.1. Registry Contents

Claim Name:  token_introspection
Claim Description:  Token introspection response
Change Controller:  IETF
Reference:  Section 5 of RFC 9701

11. References 📚🌸

11.1. Normative References 💖

[IANA.JWT] IANA, "JSON Web Token (JWT) Claims",
           <https://www.iana.org/assignments/jwt>.

[IANA.MediaTypes]
           IANA, "Media Types",
           <http://www.iana.org/assignments/media-types>.

[IANA.OAuth.Token.Introspection]
           IANA, "OAuth Token Introspection Response",
           <https://www.iana.org/assignments/oauth-parameters>.

[OpenID.Registration]
           Sakimura, N., Bradley, J., and M. Jones, "OpenID Connect
           Dynamic Client Registration 1.0 incorporating errata set
           1", November 2014, <https://openid.net/specs/openid-
           connect-registration-1_0.html>.

[RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
           Requirement Levels", BCP 14, RFC 2119,
           DOI 10.17487/RFC2119, March 1997,
           <https://www.rfc-editor.org/info/rfc2119>.

[RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
           Specifications and Registration Procedures", BCP 13,
           RFC 6838, DOI 10.17487/RFC6838, January 2013,
           <https://www.rfc-editor.org/info/rfc6838>.

[RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
           Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
           2015, <https://www.rfc-editor.org/info/rfc7515>.

[RFC7516]  Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
           RFC 7516, DOI 10.17487/RFC7516, May 2015,
           <https://www.rfc-editor.org/info/rfc7516>.

[RFC7518]  Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
           DOI 10.17487/RFC7518, May 2015,
           <https://www.rfc-editor.org/info/rfc7518>.

[RFC7519]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
           (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
           <https://www.rfc-editor.org/info/rfc7519>.

[RFC7591]  Richer, J., Ed., Jones, M., Bradley, J., Machulak, M., and
           P. Hunt, "OAuth 2.0 Dynamic Client Registration Protocol",
           RFC 7591, DOI 10.17487/RFC7591, July 2015,
           <https://www.rfc-editor.org/info/rfc7591>.

[RFC7662]  Richer, J., Ed., "OAuth 2.0 Token Introspection",
           RFC 7662, DOI 10.17487/RFC7662, October 2015,
           <https://www.rfc-editor.org/info/rfc7662>.

[RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
           2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
           May 2017, <https://www.rfc-editor.org/info/rfc8174>.

[RFC8414]  Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0
           Authorization Server Metadata", RFC 8414,
           DOI 10.17487/RFC8414, June 2018,
           <https://www.rfc-editor.org/info/rfc8414>.

[RFC8725]  Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
           Current Practices", BCP 225, RFC 8725,
           DOI 10.17487/RFC8725, February 2020,
           <https://www.rfc-editor.org/info/rfc8725>.

[RFC9325]  Sheffer, Y., Saint-Andre, P., and T. Fossati,
           "Recommendations for Secure Use of Transport Layer Security
           (TLS) and Datagram Transport Layer Security (DTLS)",
           BCP 195, RFC 9325, DOI 10.17487/RFC9325, November 2022,
           <https://www.rfc-editor.org/info/rfc9325>.

[RFC9700]  Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett,
           "Best Current Practice for OAuth 2.0 Security", BCP 240,
           RFC 9700, DOI 10.17487/RFC9700, January 2025,
           <https://www.rfc-editor.org/info/rfc9700>.

11.2. Informative References 🧠

[IANA.OAuth.Parameters]
           IANA, "OAuth Parameters",
           <http://www.iana.org/assignments/oauth-parameters>.

Acknowledgements 🙌💕

We would like to thank Petteri Stenius, Neil Madden, Filip Skokan, Tony Nadalin, Remco Schaar, Justin Richer, Takahiko Kawasaki, Benjamin Kaduk, Robert Wilton, and Roman Danyliw for their valuable feedback 🥹✨. Huge thank-yous, bestie.

Authors' Addresses 🧁

Torsten Lodderstedt (editor)
yes.com AG
Email: torsten@lodderstedt.net


Vladimir Dzhuvinov
Connect2id Ltd.
Email: vladimir@connect2id.com

📦 where this page comes from

ietf: rfc9701 2025-01
💖 girlified by claude-haiku-5-5 on 2026-10-19: a language model's rewrite of the original, under its terms