What is a BADI?
BADI stands for Business Add-In. These are like user exits but are implemented using ABAP Objects. BADI's can be implemented in every stage of the systems landscape. That means there are more than SAP and Customer specific views, but also country or language specific views. More information can be found here
How to Search BADI for a Transaction?
?Finding BADI Using CL_EXITHANDLER=>GET_INSTANCE
Go to the Transaction, for which we want to find the BADI,
Get the Program Name of Corresponding Transaction.
(Click on System->Status. Double Click on Program Name)
Once inside the program search for 'CL_EXITHANDLER=>GET_INSTANCE'.
Make sure the radio button "In main program" is checked.
A list of all the programs with call to the BADI's will be listed.
The export parameter 'EXIT_NAME' for the method GET_INSTANCE of class CL_EXITHANDLER will give you the BADI name for the Transaction.
Also have a look at the below document
*Reward if useful