which app to use for investing for starters

all of them are good, just that you need to start your journey first

You can start with Zerodha, they don’t charge any delivery brokerage (I think they charge AMC though, not sure). And groww doesn't charge any amc, but no free delivery there. Most brokers offer basic features anyway. If you’re mainly worried about brokerage and AMC, you can compare them on Chittorgarh. Some folks even use multiple brokers: one for trading, another for investments, and so on. These days, discount brokers pretty much offer everything full-service brokers do.

I am also interested to use apps..do we need money to invest?

Whatever app you use, dont think of it as a 'game' and take knee jerk reactions. Invest for the long term

Go for Groww....it's UI is good for beginners and also there is no AMC charge

Grow try Karo bro

More than half of the market share Inka hi he and also good for beginners.

Pro tip: only invest don't get into f&o till u are an expert

investing never work in right way from apps:) you will think of it as game if you start investing via apps:) because of easy interface

so my suggestion will be use web portal to learn what the things are , FORGET APPS, 

go to apps ONLY AFTER LEARNING WEB LOG IN AND THINGS because this will keep you in control of FOMO

DO NOT , JUST CHOOSE SOME OTHER PATH . 

first learn , how life works .. gain experience about things then you will have all answers . 

Zerodha.