Although for business purpose, you might prefer to choose Commercial software rather than open source, but you may also like to see what we used to use as alternative our daily software which also doing as great as commercial software.
Lazarus as alternative to Delphi
Since 2011 we decided to try Lazarus as our programming IDE.
Lazarus is a free cross-platform IDE which provides a Delphi-like development experience for Pascal and Object Pascal developers. It is developed for, and supported by, the Free Pascal compiler (Lazarus Wiki).
PSPP as alternative to SPSS
Some of us use this software in related to their educational research and this software work similar to SPSS.
PSPP is a program for statistical analysis of sampled data. It is a Free replacement for the proprietary program SPSS, and appears very similar to it with a few exceptions (PSPP Website).
ProjectLibre as alternative to Microsoft Project
If you work on a project development, you might know this software already, Microsoft Project. Recently we've found this open source software accidentally while browsing. This software name somehow remind me of LibreOffice.
ProjectLibre is an open source project management software. It intends to be a complete desktop replacement for Microsoft Project. ProjectLibre runs on the Java Platform, allowing it to run on a variety of different operating systems (ProjectLibre Wiki).Those are powerful replacement for commercial software and really worth to try.