What are some alternatives?
When comparing Flaticon and Fontello, you can also consider the following products
Font Awesome - Font Awesome makes it easy to add vector icons and social logos to your website. And version 5 is redesigned and built from the ground up!
IconPharm - IconPharm is a library of open source icons with recoloring and resizing tools.
IcoMoon - IcoMoon is an icon management tool that is build to provide iconography.
Iconfinder - Iconfinder is the leading search engine and market place for vector icons in SVG, PNG, CSH and AI format..
Nucleo - Commercial vector icons and accompanying apps to manage and customize them.
The Noun Project - Creating, Sharing and Celebrating the World's Visual Language