potrace - Open source program that transforms bitmaps into vector graphics.
ImgToText.net - This image to text converter works online to extract text from images and scanned documents without sign-up process.
Vectorizer.io - Fast and easy way to vectorize an image online
Online Image Converter - Online Image Converter converts your BMP, JPG, PNG, GIF or ICO files quickly and easily.
Autotracer.org - Free online image vectorizer
iLovePDF - Free online PDF tool set