Why Trishul Defence Academy App is the Best App | All About App Details. The App  is like a one – step solution for the Defence Aspirants . Whether it comes to Live Sessions, doubt clearing session ,video lessons ,Mock Test ,and even study material. After the great success of their offline courses , TDA has launched online classes program as well . The thought behind it is that students can easily prepare themselves even during the Lockdown period of Covid 19. TDA App is a very exclusive App for the preparation of NDA Online course under the guidance of