Microsoft 365 technician tool
Microsoft 365 Tenant Name Checker
Enter a proposed onmicrosoft.com tenant name to determine whether Microsoft Entra returns tenant metadata for it. Results are informational; Microsoft’s signup process is the final authority on availability.
.onmicrosoft.com
Use letters, numbers, and hyphens only. The name cannot begin or end with a hyphen.
Enter a tenant name to begin.
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What this checks
The tool requests Microsoft Entra OpenID configuration for the supplied tenant domain. A valid tenant response generally indicates the tenant namespace is already associated with a Microsoft 365 or Entra tenant.
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Important limitation
An inconclusive or not-found response does not guarantee the name can be registered. Microsoft may reserve names or apply additional validation during tenant creation.