[4][5][6] De Groot is considered an expert on using interpolative font design and stylistic alternates to develop large families with a wide range of features and languages supported.

[7][8] De Groot was born in the Netherlands and studied at the Royal Academy of Arts in The Hague.

[12] Thesis was initially published by Spiekermann's FontShop library before he established an independent company.

De Groot's work includes commercially released fonts and also custom families for particular clients: Corpid (previously AgroSans) for the Dutch Ministry of Agriculture; SunSans for Sun Microsystems; SpiegelSans and Taz for, respectively, the German magazines Der Spiegel[6] and die tageszeitung; and FolhSerif for the Brazilian newspaper Folha.

[15][16] Major fonts by de Groot include: As an amusement, de Groot also developed a number of parodic, spiky or distorted reworkings of Thesis, including Nebulae and JesusLovesYouAll.