One of the Original Minds Behind Microsoft Excel to Be a Honorary Guest of Bulgaria Excel Days 2025

Mike Koss is a part of the first team programmers that developed Excel 40 years ago.

As one of the lead developers who contributed to the creation of Microsoft Excel back in 1985, Mike Koss will be an honorary guest at the upcoming Bulgaria Excel Days international conference dedicated to the 40th anniversary of the legendary product, now used by nearly 1.5 billion people worldwide. He will greet participants at the event on October 22nd and will share his memories from the time when he worked as a programmer on Microsoft’s original Excel team 40 years ago.

Mike Koss is not just a software developer – he is an IT pioneer whose contributions stand behind some of the most iconic software tools in modern technology.

In 1983, after completing his master’s degree in Computer Science at the prestigious Massachusetts Institute of Technology (MIT), Mike joined Microsoft at a time when the technology world was just beginning to take shape. He soon became part of the original development team tasked with creating “the best spreadsheet product in the world” – Excel, and was shortly after promoted to team leader.

Together with lead developer Doug Klunder and his colleagues Jabe Blumenthal, Jon DeVaan, Jeff Harbers, Bob Matthews, John Hopper, and others, he made important contributions to the creation of Excel 1.0 in 1985 – a product that changed the way the world works with data. His contributions continued through version 4.0, helping Excel become and establish itself as a software standard and undisputed market leader.

During his career at Microsoft until 2002, he actively participated in the development of significant products such as Outlook, SharePoint, NetDocs Web Services, and MSN Messenger. After Microsoft, he engaged in investments in innovative companies and spent several years as a software engineer at Google.

After retiring, Mike has emerged as an activist for accessible technology education and a mentor through initiatives like Reskill Americans. His commitment to society is also reflected in his role as a board member of the Museum of Flight in Seattle, as well as his participation in various educational programs in the United States.

Beyond computers and software, Mike studied painting at the Seattle Academy of Fine Art and enjoys playing the trumpet in his free time. He continues to inspire the technology community with his belief that technology can be a force for achieving good.