Lookup external tenant id

Requirements: Authorization header and CrossTenantInformation.ReadBasic.All permission on App Registration. 

With this API endpoint you can check if the domain is registered on Microsoft 65 products and get the tenant name and tenant id by a random domain name.

Use case

This API can be used to lookup a domain name to check if this company or domain is using Microsoft 365.

Graph API

This API route can be used to lookup the tenant id and tenant name.

GET https://graph.microsoft.com/beta/tenantRelationships/findTenantInformationByDomainName(domainName='<domain>')

{
    "@odata.context": "https://graph.microsoft.com/beta/$metadata#microsoft.graph.tenantInformation",
    "tenantId": "<tenantid>",
    "federationBrandName": null,
    "displayName": "<tenantdisplayname>",
    "defaultDomainName": "<tenantonmicrosoftdomainname>"
}

Response: 200 OK

If the domain is not registered inside Microsoft 365, this API route returns a 404 Error.