xls2csv

xls2csv is a program with a name which perfectly explains its functionality - it allows you to turn Excel-supported files (XLS) into Comma Separated Values types (CSV). It can be seamlessly handled, even by first-experienced users.
This is a portable application, so installing xls2csv is not required. In other words, you can save the app to a USB flash drive or any other similar device, store it on any computer and directly run its executable file.
The most important aspect is that the Windows Registry is not updated with new entries, and no files are left behind on the hard drive after program removal. Plus, you can carry xls2csv in your pocket when you're on the go.
The interface of the application is based on a small window with an intuitive layout. The 'what you see is what you get' principle certainly applies to xls2csv, as there are no other features available, aside from the ones displayed in the main app frame.
So, you can use the file browser to select a file to convert ('drag and drop' is not supported), establish the output destination and filename, and proceed with the conversion procedure. Working with multiple entries at the same time is not possible. Moreover, you cannot preview the source or output documents, let along make any kind of modifications to the program or the conversion operation.
xls2csv runs on a low amount of system resources, has a good response time and quickly finishes a task without causing any issues, such as freezing, crashing or popping up error dialogs. Although it integrates limited features, xls2csv offers a pretty straightforward solution to XLS-to-CSV conversions. Unfortunately, no recent updates have been made.