SharePoint REST API returning DateTime field (Created) without timezone (no "Z" suffix)

Question

We are observing unusual behavior with the SharePoint REST API when retrieving Sites using:

https://org.sharepoint.com/{ServerRelativeUrl}/_api/web/

In the API response, the Created property is being returned without any timezone information, for example:

"Created": "2025-03-27T11:32:33"

Typically, ISO 8601 date-time values include either:

A Z suffix to indicate UTC:

2025-03-27T11:32:33Z

Or an explicit offset:

2025-03-27T11:32:33+00:00

However, the current response does not include any timezone indicator.
Would expect date fields with explicit offset information to avoid ambiguity.

Is this a documented schema in SharePoint REST API behavior?
Has there been a recent update or configuration change affecting date-time serialization?
Can we safely assume that returned values without timezone are UTC?

If anyone from Microsoft or the community can clarify whether this is a regression, configuration-based behavior, or by-design change, it would be greatly appreciated.

Answer 1

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Hi @******@uk.ibm.com

Thank you for posting question to Microsoft Q&A forum.

I have tested and I do see the same behavior as yours. Only Created field doesn't have the Time zone information.

 "Created": "2025-07-03T07:47:34.063",
 "LastItemModifiedDate": "2026-02-24T17:36:53Z",
 "LastItemUserModifiedDate": "2026-02-19T07:06:13Z",

I have not able to find any documents about this behavior. However, you cannot assume the value returned is in UTC.

You can try this; it will return the time in UTC time zone.

GET /_api/web/RegionalSettings/TimeZone/localTimeToUTC(@date)?@date='2025-07-03T07:47:34.063'

I also found some threads that have similar issue:

https://github.com/SharePoint/sp-dev-docs/issues/5369

Sharepoint Online REST: ListItemAllFields response DateTime timezones - SharePoint Stack Exchange

My recommendation is to report this behavior via SharePoint · Community.

I hope this information helps.

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