László is a free software activist at FSF.hu Foundation, Hungary, and free software developer since 1998, when he was a PhD student in conservation biology. Contributor of LibreOffice code base since 2002. He extended OpenOffice.org's MySpell to a real international spell checker, Hunspell, which became the de facto standard, integrated not only with LibreOffice and other open source software, but proprietary ones, e.g. PhotoShop, Adobe InDesign, macOS and Windows, spreading LibreOffice technology. Many of his unique language technology and other developments are included in LibreOffice, for example Numbertext, Lightproof and LibreLogo. In 2018–2023 he has fixed half a thousand interoperability bugs in LibreOffice, working for NISZ, the biggest ICT provider in the public sector in Hungary, and helped to solve hundreds of other bugs leading a group of LibreOffice developers. At TDF, he is currently serving his second term on the Board of Directors.