strict-rfc3339 is a simple & light python module to validate, parse and generate RFC3339 time strings. It was initially created as a part of habitat in response to difficulty using other libraries.

It can convert UNIX timestamps to and from RFC3339, either producing strings with a UTC offset (Z) or with the offset that the C time module reports is the local timezone offset. It has minimal dependencies (none beyond those that come with Python) and avoids the error-prone act of dealing with timezones as much as possible. Besides that, it's designed to be strict and stick closely to RFC3339, with a couple of very small caveats. It's also fully unit tested.