Resolver One uses the Python programming language, which was first released in 1991. Python is an easily learnable and highly expressive language with a rich standard library; it has been successfully used in a wide variety of applications, in businesses and in academia. Its clean syntax allows newcomers to become productive rapidly, while its more sophisticated features and built-in test framework allow experienced developers to build powerful tools which can adapt quickly to changing requirements.

Louis Jaouan, Director of Financial Risk at Credit Cooperatif, commented: "In the Financial Risk department, in order to rapidly respond to new needs, we have to write a number of tools ourselves, to access different sources of information and manipulate them, all without having to go to our IT department. We use Excel and VBA, but we prefer Python for its combination of simplicity and power. We were looking to better link spreadsheets with Python programming, and Resolver One seemed to be the most elegant solution because it was based on Python but also gave us compatibility with our IT team's architectural choice of Microsoft .NET. We had been looking at using IronPython for a year but were hesitant to take the first step until we saw the elegant and secure environment provided by Resolver One. I signed up as a beta user as soon as I learned of its existence. Its original conception is intellectually elegant and even though we so far use only a fraction of its capabilities, we have already witnessed a significant increase in the speed at which we deploy new control tools."