Decilog was founded more than 50 years ago by John Marchesano - a business-minded engineer from Long Island, New York. He formed Decilog as a quick-reaction technical services company providing high-level scientific, engineering, and management support to government and commercial industry. Through today, Decilog has maintained John’s vision and continues to solve sophisticated problems and offer services relating to conceptual design, requirements development, system analysis, software engineering, rigorous testing, and software assurance and training. A particular strength of Decilog’s professional team is developing and testing leading-edge security-critical control and information systems.

The company headquarters are located in Melville, New York, housing many of our dedicated staff of systems and software engineers. We also establish key offices at our clients’ facilities in order to efficiently and productively conduct requirements development, testing, and training. We select the most cost-effective approach and structure for each and every assignment.


Systems Engineering   •   Software Development & Design   •   System Testing & Assurance
Simulation & Training   •   Homeland Security   •   Cybersecurity