potrace - Open source program that transforms bitmaps into vector graphics.
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
Vectorizer.io - Fast and easy way to vectorize an image online
Sumatra PDF - Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.
Autotracer.org - Free online image vectorizer
Wondershare PDFelement - All-in-one PDF editor