This is a compact tool which allows you to merge your pdf files resulting in one final document.
It is written in Python 3 and uses Python's tkinter for the GUI realization.
The PyPDF2 library needs to be installed beforehand. Use the package manager pip to install PyPDF2.
pip install PyPDF2
Open your cmd and navigate to the folder where pdfmerger.py is. Now simply type:
python pdfmerger.py
The GUI will open up and you can start merging your files.