---
id: api-oauth-token-introspection
title: 'API OAuth Token Introspection'
schema_type: TechArticle
category: computer-science
language: en
confidence: medium
last_verified: '2026-06-02'
created_date: '2026-06-02'
generation_method: ai_structured
derived_from_human_seed: true
conflict_of_interest: none_declared
is_live_document: false
data_period: static
atomic_facts:
  - id: fact-computer-science-api-oauth-token-introspection-1
    statement: >-
      RFC 7662 defines a method for a protected resource to query an authorization server to determine the active state and metadata of an OAuth token.
    source_title: RFC 7662 OAuth 2.0 Token Introspection
    source_url: https://datatracker.ietf.org/doc/html/rfc7662
    confidence: medium
  - id: fact-computer-science-api-oauth-token-introspection-2
    statement: >-
      Duende IdentityServer documentation describes an introspection endpoint that implements the OAuth 2.0 token introspection specification.
    source_title: Duende IdentityServer Introspection Endpoint
    source_url: https://docs.duendesoftware.com/identityserver/reference/endpoints/introspection/
    confidence: medium
  - id: fact-computer-science-api-oauth-token-introspection-3
    statement: >-
      Keycloak OpenID Connect layer documentation includes a token introspection endpoint for obtaining token metadata.
    source_title: Keycloak OIDC Layers
    source_url: https://www.keycloak.org/securing-apps/oidc-layers
    confidence: medium
completeness: 0.83
known_gaps:
  - Introspection latency, caching, token type, audience, scope semantics, and revocation timing differ across authorization servers.
disputed_statements: []
primary_sources:
  - title: RFC 7662 OAuth 2.0 Token Introspection
    type: standard
    year: 2015
    url: https://datatracker.ietf.org/doc/html/rfc7662
    institution: IETF
  - title: Duende IdentityServer Introspection Endpoint
    type: documentation
    year: 2026
    url: https://docs.duendesoftware.com/identityserver/reference/endpoints/introspection/
    institution: Duende Software
  - title: Keycloak OIDC Layers
    type: documentation
    year: 2026
    url: https://www.keycloak.org/securing-apps/oidc-layers
    institution: Keycloak
secondary_sources: []
updated: '2026-06-02'
ai_models:
  - gpt-5-codex
---

## TL;DR

OAuth token introspection lets APIs ask an authorization server whether a token is active and what metadata is associated with it.

## Core Explanation

Agents working on APIs should understand when a resource server validates a token locally and when it calls an introspection endpoint. Introspection can support opaque tokens, revocation checks, and centralized policy, but it also introduces network and caching behavior.

Agents should not assume that a successful introspection response means the caller is authorized for every action. Scope, audience, issuer, tenant, and application policy still need explicit checks.

## Source-Mapped Facts

- RFC 7662 defines a method for a protected resource to query an authorization server to determine the active state and metadata of an OAuth token. ([source](https://datatracker.ietf.org/doc/html/rfc7662))
- Duende IdentityServer documentation describes an introspection endpoint that implements the OAuth 2.0 token introspection specification. ([source](https://docs.duendesoftware.com/identityserver/reference/endpoints/introspection/))
- Keycloak OpenID Connect layer documentation includes a token introspection endpoint for obtaining token metadata. ([source](https://www.keycloak.org/securing-apps/oidc-layers))

## Further Reading

- [RFC 7662 OAuth 2.0 Token Introspection](https://datatracker.ietf.org/doc/html/rfc7662)
- [Duende IdentityServer Introspection Endpoint](https://docs.duendesoftware.com/identityserver/reference/endpoints/introspection/)
- [Keycloak OIDC Layers](https://www.keycloak.org/securing-apps/oidc-layers)