The Fast Fourier Transform (FFT) algorithm that calculates the Discrete Fourier Transform (DFT) is one of the major breakthroughs in scientific computing and is now an indispensable tool in a vast number of fields. Unfortunately, software applications that provide fast computation of DFT via FFT differ vastly in functionality and lack uniformity. A widely accepted Applications Programmer Interface (API) for DFT would advance the field of scientific computing significantly. In this article, we present the specification of DFTI, a new interface that combines functionality with ease of use. This API is our strawman proposal toward a common interface for DFT calculations.