How do I get a job at Amazon, Flipkart, etc.?

I think I am best to give this answer ;)

Amazon and Flipkart’s work culture is like startup, you should work fast and produce result which is almost bug free (no code is ever 100% bug free). And if error in your code comes, They require you to act asap basis along with other work. So their hiring process is created in a way that finds best match.

You might know about rounds for Amazon, Flipkart , but let me write it,

1 round : for coding ,amazon give on hackerrank or hackerearth, Flipkart asks Machine coding on the spot. For Amazon there can be Data Structure and Algorithm questions see here. For Flipkart You have to have handson experience on coding no predefined DS questions are asked ( So Flipkart Interview’s First step itself will be tougher than of Amazon’s)
2nd and/or 3rd round : In Amazon will be on DS and Algo questions which are difficult ones like Dynamic Programming or 2d Matrix recursion or Algo questions. and Same for Flipkart see such questions here .
4th round : would be for Design round where you have to design a system say Linkedin or Vending Machine or multi story car parking etc.

Last would be Hiring Manager, where he can ask any thing, how u handle git or design payment gateway or any thing comes in his mind.
If in all rounds your score is good, You are selected :)

To prepare for such interviews you can start from gohired.in site and then move to GeekforGeeks .
Adapt thinking pattern in order to solve any question rather than mugging any code or logic, and main thing Do coding for all questions.

If you want to learn how to crack such interview from a mentor, please ask your questions doubts to GoHired