The Data Alignment Tool (DAT) was built to assist with the analysis of data used in testing Fault Detection and Diagnostics (FDD) tools and building commissioning (Cx) tools. The data sources were the Virtual Cybernetic Building Testbed (VCBT) and data collected from real buildings. The raw data processed by the DAT typically spanned multiple input files, and was not in a format appropriate for the analysis tools. The features provided by the DAT were implemented to address our specific needs, but should also be applicable to a wide range of other uses. The DAT can read data from one or more data files, perform several useful operations on it, and save it with a variety of options. The operations implemented include combining subsets of columns from multiple data files into one output file, reducing data by modifying the time span between data points, performing unit conversions, and filtering data by time of day. Output file operations include a column filter or splitting out files by date. As a manual process, each of these operations would be time consuming, tedious and error prone. The DAT largely automates these operations.