I got myself a bearer token by calling https://login.microsoftonline.com/{tenantId}/oauth2/v2.0/token with the scope https://{tenantName}.sharepoint.com/.default
It's a token for a registered app in Azure AD.
When I use that token to make an API call like https://infoinnobake.sharepoint.com/_api/search/query?querytext='contentclass:STS_Site contentclass:SP.Webb'&selectproperties='Title,Path'&rowlimit=500
I only reveice 401 Unsupported app only token.
can some explain why? Is it possible to access the sharepoint online API with an registered App on Azure AD?
Follow this guide right here: https://learn.microsoft.com/en-us/sharepoint/dev/solution-guidance/security-apponly-azuread
you need to create a certificate and upload the certificate to the registered app. Than you can use the API or the SharepointClient in various programming languages