CSVDataMerge automatically merges together CSV (comma-separated value) datafiles into one larger dataset. It is assumed that individual datafiles are in comma-separated CSV or TXT format. If datafiles have a header row (i.e., column names) at the top of each file, the program does not assume that columns are in the same order for all datafiles (it will resort them if not) or that all datafiles have the same columns. The program also deals correctly with empty cells, commas within cells, and quoted text. The user only needs to (a) ensure that Java is installed on the computer, (b) place the JAR file (CSVDataMerge.jar) in the corresponding folder, and (c) create a folder called "data" (case sensitive) in the same folder as the JAR file, which in turn stores all of the CSV or TXT files (and nothing else). Double-clicking on the JAR file will create a file called dataset.csv (the concatenated file). For some other uses (see source article), a headers.csv file is also needed. For developers, The source code can be found in the following GitHub repository: https://github.com/james-schmidt/CSVDataMerge The JAR file and JAVA code are also provided here. If you use CSVDataMerge for your research please cite: Schmidt, J. R. (2021). CSVDataMerge: A Simple and Free Program for Concatenating Experimental Data Files. Submitted for publication. GNU General Public License v3.0 (see GitHub repository).