Open Source C Date Calculators

Osmo is a handy personal organizer, which includes calendar, tasks manager, address book and notes modules. It was designed to be a small, easy to use and good looking PIM tool to help to manage personal information.

NOTE: Moved to https://github.com/vapier/pcalc Pcalc is a command line calculator handling HEX DEC OCT BIN. It can process a script, save variables to file, full math parser, parentheses, exponential, sin/cos, sqrt, date, inch/mm celsius/f, compound expressions ...

A simple command to convert calendar dates to julian dates. Quite useful in timing situations where you need elapsed time between dates. Also useful for astronomy applications.

With this application you will know, instantly the time difference between two dates in the form of date, days, hours, minutes, and seconds!

So who wants to fire up Google, Outlook, or other gigantic program just for a quick look at a calendar? No one. Here is a simple calendar, a 6 month view, too simple really, but useful. A bit more useful since one can also find the # of days from a start day to an end day, inclusive. Also it can be used to show the resulting date once given a start date and +/- a number of days. Lastly, it can also set a simple alert for a date & time. This is a one shot alert, no repeat function. Version 2.0.2 supports four 'Methods' to schedule an alert; VBS, PowerShell 5.1, C, and PowerShell 7. The 'Method' to use can be selected, but defaults to C if no selection is made. An ini file has been added to store the 'Method' chosen. It can be run from a USB, just three files, nothing written to the registry, no phone home or telemetry. Simple calendar with a few 'extras' thrown in... Simple, free, small footprint, but hopefully useful. Version 2.0.2 released 8/7/2026