The national airline of India is Air India but the largest airline of India is Indigo. Other scheduled airlines include SpiceJet, Vistara, Air Asia, Akasa Air, Alliance Air, Star Air, Flybig, Air India Express, Air Connect, Fly91, Spirit Air and IndiaOne Air. All these together operate close to 750 aircrafts. I have not missed Go First, just held it out of the list because its going through turbulent weather.
Next is the list of non schedules operators starting with Pawan Hans, Global Heli Corp, Heli Go, Air Charter Services, Indo Pacific Aviation, Aryan Aviation, Jet Aviation, Himalayan Heli Services, India Fly Safe, Aero Trans, Maharaja Aviation, Deccan Air, Chipsan Aviation, Heritage Aviation, Arrow Aircrafts, Kestrel Aviation, Blue Ray Aviation, Dhillion Aviation, Red Bird Airways, Aman Aviation and a few others. Together all these operate close to 200 aircrafts.
Hot Air Ballooning India has a special mention here as it operates hot air balloons near Delhi.