Introducing an open source project, FontTester. A FLTK project GUI application that supports multi-platforms ( Windows, Linux, MacOSX ) with these libraries: Freetype2 and FLFTRender.
Anybody can join to project, or write any issues, or just download prebuilt image at downloading page.
It’s free. Test your TTF/TTC/OTF without install to system. Type any words on input area and drag or load yor font file to rendering area or click “Load Font” button. and just try to render it. Simple.