The role of Indian Air Force is to secure the Indian airspace and provide air defence against hostile aircrafts and missiles. It is also working to provide Ballistic Missile Defence.
Here, I have listed down most of the systems used by IAF to provide the air defence.
Akash SRSAM: 25 to 40 km
Protection of air bases. Acting as the second line of defence
Quantity: 15 squadrons
Spyder QRSAM: 15 to 50 km
Quick reaction system for protection of vulnerable points
Quantity: 04 squadrons
MRSAM/Barak-8: 70 to 110 km
Protection of vulnerable areas and key military installations by providing area air defence.
Quantity: 24 FUs
Akash NG: 80 km
Low Level Quick Reaction system for protection of air bases and vulnerable points. It will supplement the Spyder.
Quantity: 7 to 10 squadrons*
Pechora: 15 to 20SRSAM for protection of airbases and key military installations. It will be replaced by MRSAM + Akash NG.
Quantity: 25 squadrons
S-400: 250 to 400 km
Long range area air defence and air space denial.
Quantity: 5 squadrons
AAD: Part of the BMD Network Phase -1.
Endo-atmospheric missile against the 1500km range targets.
PDV: Part of the BMD Network Phase-1. Exo-atmospheric missile against the 3000km range targets.
PDV MK-2: ASAT missile. It can neutralize targets in the space orbit.
AD-1: Part of BMD Network Phase-2. Endo-atmospheric missile against the 5000 km range targets.
AD-2: Part of BMD Network Phase-2. Exo-atmospheric missile against the 5000 km range targets.
ERSAM: Part of ERADS system. Long range area air defence and air space denial. Quantity: 7 squadrons*
XRSAM: Part of ERADS system. Long range area air defence and air space denial. Quantity– 7 squadrons*
AA Guns: Protection of air bases by acting as the last line of defence.
Quantity: 244*
VSHORADS: Man-portable system against helicopters, UAV, and slow-moving aircrafts.
Aside from the systems mentioned above some other systems are also available but I am not sure if they are still in service or not and what is their exact quantity. They are:
S-200
S-300
Kub (SA-6 Gainful)
9K33 Osa (SA-8 Gecko)
Upgraded Bofors L70
9K338 Igla-S
Some systems which might find their way in IAF:
Truck based VL-SRSAM
DEW
@Acetic Acid