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Ora is a freestanding time and date implementation for C++ and Python.

Docs at


Many Python time libraries already exist, including the standard library datetime module.

Ora provides:

  • An opinionated, concise API centered around physical times.
  • Built-in time zones.
  • High performance for all operations.
  • Multiple widths and precisions for times and dates.
  • Rich C++ interoperability.

Ora is not a drop-in replacement for datetime or other Python time libraries, but supports easy interoperability.


Ora is currently prerelease software; bugs are plentiful, and APIs are subject to change.


Similar to datetime, Ora uses the (proleptic) Gregorian calendar, for years 1 – 9999 only. Alternate calendars and B.C.E. dates are not provided. There is no support for leap seconds, relativistic effects, or astronomical times. However, time precision of 1 ns or smaller is supported.


  • Requires C++14 and Python 3.6+.
  • Tested on Linux and MacOS. Currently no Windows support.
  • Tested on x86-64 only.


Ora is distributed:

  • On PyPI, as source and Linux x64 / MacOS binary wheels:

    pip install ora
  • On Anaconda, as Linux x64 / MacOS conda packages:

    conda install -c alexhsamuel ora
  • On GitHub.

Building from source requires a C++14 compiler. See for more information.

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