ISO datetime regex pattern

Copy and test a JavaScript regex for ISO datetime strings, with examples, limitations, and a one-click link to the regex tester.

Use anchors to check whether the complete value matches.

Regex: ^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}(?::\d{2})?(?:\.\d{1,3})?(?:Z|[+-]\d{2}:\d{2})$

Flags: -

Find matching fragments inside a larger block of text.

Regex: \b\d{4}-\d{2}-\d{2}T\d{2}:\d{2}(?::\d{2})?(?:\.\d{1,3})?(?:Z|[+-]\d{2}:\d{2})\b

Flags: g

Limitations

This pattern matches common ISO datetime shapes but does not prove that the timestamp is a valid calendar moment.