Forex Tester API allows you to create and install your own indicator or strategy (Expert Adviser) to Forex Tester. API is available for C++ and Borland Delphi (Object Pascal) languages. It is set of files (with useful functions) that you attach to your project to compile resulting *.dll file. Then you can install this file in Forex Tester. You can find API files after installation of Forex Tester in <ForexTester>\Examles\ folder with indicators and strategies examples.
I can recommend to use next tools to compile your projects. API was tested with these tools and they work fine. Also some of them are absolutely free to use even in commercial purpose:
1. Borland Delphi
- any Delphi version starting from Delphi 7. Unfortunately it is not free now (they provided free Turbo Delphi Explorer before). You can see Delphi tutorials here: http://www.forextester.com/forum/viewforum.php?f=9
- free cross platform pascal compiler. Can compile Delphi code without problems. You can download it here: http://sourceforge.net/projects/lazarus/files/Lazarus%20Windows%2032%20bits/Lazarus%126.96.36.199/lazarus-0.9.26.2-fpc-2.2.2-win32.exe/download
See how to install it and compile indicator in this video: http://www.youtube.com/watch?v=kL7z8kG7WCw
3. Microsoft Visual C++
2005 Express Edition (you can download this tool from Microsoft site http://www.microsoft.com
) - it is also free. Or you can use other C++ compilers.