All the transaction codes in SAP system are listed in table TSTC.
If you want find the transaction codes based on SAP modules, you can do the following steps,
1. Execute transaction code SE16, fill the table name as TSTC and press F4 button. You will prompted with below screen.
2. Highlight your mouse cursor at Application Component tab and press F4 button again. The next screen will show the transaction codes based on SAP modules. You can expand the subtree to list the available transaction codes.
