Vectorizer.io - Fast and easy way to vectorize an image online
theonlineconverter.com - Theonlineconverter.com is an online file conversion platform which offers a user-friendly, cross-platform online tools for user's diverse needs. It allows batch conversion of files and is completely free of cost.
Autotracer.org - Free online image vectorizer
ConvertOnMac - ConvertOnMac is the best free online converter for every Mac user that supports more than 500 different file formats.
potrace - Open source program that transforms bitmaps into vector graphics.
Convertio Vector Converter - Convertio Vector Converter is a unique platform that offers you to convert the vector into any format.