The QuickBooks Online API uses OpenID Connect for user authentication and the OAuth 2.0 protocol for authorization.
Your app's authentication and authorization requirements depend on how you plan to publish it. Use this flowchart to determine how you want to publish your app and understand what you will need to implement.
Listed on app store with Intuit single sign-on enabled: users sign up using the app store Get App Now button.
Listed on app store without Intuit single sign-on enabled: users are redirected to your app's landing page via app store Learn More button.
Not listed on app store: developer controls availability and distribution of the app.
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