I produce some free open source software, mostly small libraries and utilities, many listed in the Site Map. And many years ago I also created a free open source DiffPDF application, now long maintained by others.
All of my books are published by Pearson Education (under various imprints), although they are all out of date now with no prospect of new editions.
A bit about me; I can be contacted as m.n.summerfield (gmail—dot com).
I founded Qtrac Ltd. in 2006. The company traded until 2024, and was
wound up in 2025. Its website was www.qtrac.eu.
The “Qtrac” in Qtrac Ltd. stood for “Quality Training Research And Consultancy”. Qtrac Ltd. began with the intention of providing programming training courses. However, in its first eight years it mostly earned money from the books written by me its owner and sole employee, plus income from providing technical writing services and programming training courses. During Qtrac Ltd.'s last decade, most of its income was generated by license sales of its PDF comparison products, in particular the DiffPDF GUI application and the more technical comparepdfcmd tool (itself the successor to the diffpdfc tool). In 2023 Qtrac Ltd. stopped selling its software to European customers due to the EU's Cyber Resiliance Act. This cost Qtrac Ltd. about half its sales. Nonetheless the company continued. For almost eleven years Qtrac Ltd. sold its software using Digital River/MyCommerce (DRMC) to handle the payments. Unfortunately, from mid-2024 DRMC stopped passing on the money it received to its customers. DRMC went bankrupt in early 2025. This led directly to Qtrac Ltd.'s closure in 2025.
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