Isotope (or isopat, for "isotope pattern Calculator") is a small command-line utility to calculate the isotope pattern for a given chemical formula.
In contrast to most programs that I came across, this one is not an application with a graphical interface, but but a small stand-alone utility. It allows to run calculations in batch mode, via the command line, or (using a webserver) via a web interface. You can easily integrate it into your laboratory workflow, even using fully automated data processing.
To build the software, just a standard-compatible C compiler is required; please see the documentation.
For use with a web server, a web server (preferably Apache) with Perl CGI is required. The installation is described in detail in the documentation.
The software is in use since 1996. It has been updated a few times, but no major changes were introduced. I have good reasons to believe that it is in a stable state; there are currrently no plans for further development.
This software is Free Software and is published under Version 2 of the GNU General Public License (GPL). You can redistribute it and/or modify it under the same terms, which ensures that its source code is free and that any derivatization, or implementation of it in other software, will also remain free.
The difference between "free software" and "freeware" is of legal importance. If you do not understand any portion of this license, please seek appropriate professional legal advice. If you do not or if - for any reason - you can not accept all of the conditions of the GPL, then you must not use nor distribute this software.
Since early 2009, this project is hosted at sourceforge.net. To download, you have several possibilities:
The author is Jörg Hau.