The font used in the images was generated by metaflop.  (See http://www.metaflop.com/modulator for more details about metaflop.)  As the website notes: "All outline-based fonts (webfonts or otf) that are generated with this project are licensed under the SIL Open Font License v1.1 (OFL). This means that you can freely use and extend the fonts and also use them commercially. Any derivative work has to be made freely available under the same license."
