Shubh Muhurat is essentially time to perform auspicious work. You can call it a good time to start business, travel, Marriage, Puja, Griha Pravesh, etc. An auspicious time or Shubh Muhurat of the day depends on many factors like the relative position of transit planets and planets in your Kundli. Astrologycal.com provides Muhurat timings of all days and nights for all cities in the world for free. Good Muhurat like Choghadiya, Gowri Panchangam, and Shubh Hora.
Astrologycal.com also provides inauspicious times like Rahu Kaal which should be avoided for all Shubh Work.