Anthony Henry Koester, 83, of St. Louis, Missouri, born January 25, 1943, and baptized into the Catholic faith, was called home to the Lord on February 21, 2026. Surrounded by the love of his family, he entered into eternal rest, strengthened by the sacraments and sustained by the promise of the Resurrection.

He was the beloved husband of 61 years to Joan (Kaiser) Koester, a devoted and loving partner whose marriage stood as a testament to faith, loyalty, and enduring love.

Tony was a proud and loving father to Angie Wagner (Dan), Chris Koester (Sierra), and Emily Wilson (Eric). His greatest joy was his family, and he carried deep pride in each of his children and the lives they built.

He was the cherished grandfather of Kate Hill (Rick), Cameron Koester, Brianna Koester, Ashley Koester, Brendon Koester, Izzy Wilson, Jake Wagner, and Ben Wilson, each of whom brought him immeasurable joy and pride.

He was preceded in death by his parents, Arthur and Loraine Koester, and his sister, Carolyn Koester. He is survived by his sister, MaryLou McDowell (Dave).

Tony's strong work ethic began early. While putting himself through college, he founded a television repair business called Smitty's and also worked at Granite City Steel. His drive and determination would define his professional life.

He began his career at McDonnell Aircraft Corporation, where he gained the experience and knowledge that would shape his future in technology. He later joined Monsanto, where he wrote 24,000 lines of code that helped launch the first rocket into space. He continued building his respected career at The MITRE Corporation, contributing his expertise in innovation and systems development.

With an entrepreneurial spirit, Tony co-founded Interface Technology, successfully growing and eventually selling the company. In 1991, he founded American Technology Corporation, where he combined leadership, vision, and technical expertise. Even after stepping away from ownership, he continued consulting for numerous organizations, sharing his knowledge and mentorship until his retirement from Aspire Software in 2017.

From a young age, Tony devoted his time to serving others. He quietly fed the poor, supported the Pink Sisters, and collected cans that he delivered into the city so those experiencing homelessness could redeem them for money. After retirement, he continued his service in St. Louis through the St. Vincent de Paul Society, counseling and assisting individuals in need with compassion and dignity. In recognition of his faith-filled service and commitment to others, he was named Man of the Year in 2016 by the Archdiocese of St. Louis. His Catholic faith was the foundation of his life, and he was an active and devoted member of St. Monica and Incarnate Word parishes.

In his quieter moments, Tony found joy in simple, steady pursuits. He enjoyed splitting logs, fishing, watching hummingbirds, and faithfully praying the 3:15 daily Rosary. He appreciated the rhythm of nature and the peace it brought, reflecting the steady, humble spirit that defined his life.

Visitation will be held on Friday, March 6, from 10:00 a.m. to 11:30 a.m., followed by a Funeral Mass at 11:30 a.m. at Incarnate Word Parish. A private burial will follow.

In lieu of flowers, memorial donations may be made to St. Vincent de Paul or Caring and Sharing Food Pantry of Wentzville.

Ortmann Stipanovich Funeral Home
www.osfuneralhomes.com