Jagannatha Hora is a Vedic astrology software. In terms of the range of calculations available, technical depth and breadth, level of customizability of calculations and ease of use, Jagannatha Hora is unsurpassed by any contemporary Vedic astrology software package.
Morinus is an easy to use astrology software under GPLv3 license. It uses the swiss ephemeris so it's very accurate (5000BC - 5000AD). It runs on every Operating System where Python and wxPython are available(Linux, Unix, Windows, MacOS).