Julius is a simple converter for the translation of numbers written with arabic digits into roman digits, and it is able to translate roman numbers in arabic ones.
The use of Julius if very easy: First choose the direction with the tabs (1->I: arabic to roman and I ->1: roman to arabic), then simply write (or paste) the number (under 4000, and strictly positive with no decimal if typed in arabic), click on the convert button, and the converted number is displayed, in a copy-enabled field.