Jadx

If you are an Android developer, you probably understand that building, testing or debugging applications would be impossible without appropriate software assistance.
Fortunately, nowadays there is a huge selection of products that can help you achieve quick, convenient results. One of these programs is Jadx.

Portable tool

Since it is portable, this application does not require you to install it on the target computer, as simply unpacking the archive it comes in and launching the executable grants you full access to its controls.
More so, that means it won't tamper with any of your Windows registry entries, nor will it create additional files or folders on your computer without your explicit permission.

Graphic and Command Line Interface

This application can be used in CMD and GUI modes, depending on the user's preferences. After you decompress the archive, you will find two executables in the Bin folder. A "jadx" file that can be used to run the CMD version and a "jadx-gui" one if you'd prefer using the application with a Graphic User Interface.
However, you should keep in mind that for the GUI version, Java Runtime Environment needs to be installed on your computer so that it can be run as intended.

Converts various files to DEX

You can turn to Jadx if you need a quick way to convert various files to DEX format. Among the supported formats you can find  APK, DEX, JAR, CLASS and ZIP. After you import a file, you can view its source code, resources and corresponding packs by using the tree view in the left part of the window.
It is possible to interact with the opened contents from the central section of the window. The code can be selected,copied, cut, pasted or deleted, according to your needs.

Portable DEX converter that comes with a GUI and a CMD component

All things considered, Jadx is a lightweight application that lets you convert various files to DEX format easily. It doesn't require installation, features a GUI and a CMD component and enables you to interact with the source codes of your apps.