curl --request POST \
  --url https://api.hubapi.com/oauth/2026-03/token/introspect \
  --header 'Content-Type: application/x-www-form-urlencoded' \
  --data 'client_id=<string>' \
  --data 'client_secret=<string>' \
  --data 'token=<string>' \
  --data 'token_type_hint=<string>'

{
  "active": true,
  "app_id": 123,
  "client_id": "<string>",
  "expires_in": 123,
  "hub_id": 123,
  "is_private_distribution": true,
  "scopes": [
    "<string>"
  ],
  "signed_access_token": {
    "appId": 123,
    "appInstallId": "<string>",
    "audience": "<string>",
    "expiresAt": 123,
    "hubId": 123,
    "hublet": "<string>",
    "installingUserId": 123,
    "isPrivateDistribution": true,
    "isServiceAccount": true,
    "isUserLevel": true,
    "newSignature": "<string>",
    "scopeToScopeGroupPks": "<string>",
    "scopes": "<string>",
    "signature": "<string>",
    "trialScopeToScopeGroupPks": "<string>",
    "trialScopes": "<string>",
    "userId": 123
  },
  "token": "<string>",
  "token_type": "<string>",
  "token_use": "access_token",
  "user_id": 123,
  "hub_domain": "<string>",
  "user": "<string>"
}