Pathology or Diagnostics is an important part of healthcare. India has been blessed with lots of national labs.

Metropolis Mumbai (Linkedin, Twitter, Facebook, Instagram, Youtube, Play Store)
SRL Delhi (Linkedin, Twitter, Facebook, Instagram, Youtube, Play Store)
Thyrocare
Dr Lal Path Labs (Linkedin, Twitter, Facebook, Play Store)
Suburban (Linkedin, Twitter, Facebook, Instagram, Play Store)
Apollo Diagnostics (Linkedin, Twitter, Facebook, Instagram, Play Store)
Max Healthcare (Linkedin, Twitter, Facebook, Instagram, Play Store)
Red Cliffe Labs

All National Hospital Chains offer Pathology / Diagnostics services like
Narayana Health (Linkedin, Twitter, Facebook, Instagram, Play Store)
Fortis Hospitals (Linkedin, Twitter, Facebook, Instagram, Play Store)
Medanta Hospitals (Linkedin, Twitter, Facebook, Instagram, Play Store)

And almost all digital health startups offer pathology / diagnostic services like
1mg (Linkedin, Twitter, Facebook, Instagram, Play Store)
PharmEasy (Linkedin, Twitter, Facebook, Instagram, Play Store)
MFine (Linkedin, Twitter, Facebook, Instagram, Play Store)
Practo (Linkedin, Twitter, Facebook, Instagram, Play Store)
Healthians (Linkedin, Twitter, Facebook, Instagram, Play Store)
Portea (Linkedin, Twitter, Facebook, Instagram, Play Store)
Curefit (Linkedin, Twitter, Facebook, Instagram, Play Store)
Pristyn (Linkedin, Twitter, Facebook, Instagram, Play Store)
Netmeds (Linkedin, Twitter, Facebook, Instagram, Play Store)
HealthifyMe (Linkedin, Twitter, Facebook, Instagram, Play Store)
Krsnaa (Linkedin, Twitter, Facebook, Instagram, Play Store)
Medi Buddy (Linkedin, Twitter, Facebook, Instagram, Play Store)