Top-Down Software, Inc is an organization of contributing professionals that design and develop software and database-system solutions for domestic and international clients. It is a small American business incorporated in and operating under the laws of the State of Maryland.

Led by Gary Mrenak, TDSI's founder and president, contributing professionals have come from academia and from industry, bringing with them the perspectives of both the theoretician/researcher and of the practitioner. They have represented substantial software development experience, and among them have published several textbooks and numerous papers. Many of these professionals have faculty experience teaching computer science, software engineering, and programming from the junior college through graduate levels.