Picking up an older topic... It would be a real enhancement for the online compiler to support C-files. I already ported a couple of OpenSource libraries (libtiff, mad, uip, etc) to the mbed platform. In most cases it is some work to get them to compile as C++, but it works. At the moment I managed to get FreeRTOS running on MBED with the Keil compiler (which I understand is the backend for the online compiler). Switching to C++ makes the code stop working. I mean this is really bare-bone code, hacking the stack, mixed with assembler, and I doubt getting it to work as C++ code. C++ and C have a long common history and mixing C and C++ was one of the goals of Bjanrne Stroustrup from the beginning. I understand your objections but if you want to make the online compiler a real alternative to offline tools, I think C support is essential on the long run. Regards Andreas