SNAPSHOT is a software platform designed to eventually replace Holdup Measurement System 4 (HMS 4), which is the current state-of-the-art for acquisition and analysis of nondestructive assay measurement data for in situ nuclear materials, holdup, in support of criticality safety and material control and accounting. HMS 4 is over 10 years old and is currently unsustainable due to hardware and software incompatibilities that have arisen from advances in detector electronics, primarily updates to multi-channel analyzers (MCAs), and both computer and handheld operating systems. SNAPSHOT is a complete redesign of HMS 4 that addresses the issue of compatibility with modern MCAs and operating systems and that is designed with a flexible architecture to support long-term sustainability. It also provides an updated and more user friendly interface and is being developed under an NQA 1 software quality assurance (SQA) program to facilitate site acceptance for safety-related applications. This paper provides an overview of the SNAPSHOT project including details of the software development process, the SQA program, and the architecture designed to support sustainability.