How to see source code of any APK file or app ?

Question

Can anyone see source code of any APK file or app ?
If yes then
how ?

Answer 1

I do it as follow:
Requirements:
dateimanager+ (app for android)
apktool (programm for linux, but maybe it runs on windows, I dont try it)

Steps:
open dateimanager+
Search apps and touch it
Look for targetapp
Touch it, hold
Select "backup" & confirm
go to "remote"
Select "over wifi"
At pc open browser & search for the backup
Download it
Open downlods in console
Use apktool -d filename

--
You should have a new directory with the decompiled files.

Startin with the AndroidManifest and so called smali files.

This is, where the party goes on.
Its a big puzzle and its good if you have knowledge about java and kotlin.

But only the AndroidManifest.xml is interesting to see, read & compare with other manifest-files..

Have fun :D

Answer 2

An apk file is actually a zip file, just change its extension from .apk to .zip. Then you will get some dex file. To convert those file into java you can use tools like dextojar.
Thank you