[yaantc]

mbed is only for ARM based systems (license limitation, not technology related), and in the embedded world there's much more than ARM.

FreeRTOS is easy to use on any and all CPU architectures, and is much more common. Actually, FreeRTOS is the most popular RTOS in the embedded world with Linux, and uptrending (see https://m.eet.com/media/1246048/2017-embedded-market-study.p... slides 62/63). This is a survey of professional embedded developers, not newcomers. Notice than mbed doesn't even show up. My feel is that mbed can be attractive to newcomers in embedded (easiness), but has not (yet?) much traction with people already doing embedded dev.

[nicolas314]

Good point: Mbed OS is only for ARM-based processors. The main difference lies in the vast number of drivers it offers, which is the reason why you already have 100+ supported boards today. In comparison, FreeRTOS would run on any MPU but without drivers you won't go far.