The primary software component of embedded systems is the operating system, or OS. The OS is integrated with the underlying hardware chosen for the project and manages the hardware and software resources of the system. It also provides common services to enable applications to easily run with underlying hardware. The OS can manage functions, schedule tasks, maximize performance, respond to interrupts and external I/O, share and protect system resources (such as files), and enable connection to different networks. Operating systems can also provide a layer of security to help protect the device and the data it generates from malicious attacks.

Embedded systems use different types of operating systems:

Real-time operating systems (RTOSes)

Embedded systems have traditionally used real-time operating systems for devices of all kinds. RTOSes provide high performance, a small footprint, low-latency (real-time) responsiveness, and deterministic behavior. Devices and machines with mission-critical, safety-critical, and functional safety requirements rely on an RTOS to execute applications on time and as expected, without fail. VxWorks is an example of a market-leading commercial RTOS.

There are also RTOSes supported by open source community projects including FreeRTOS and Zephyr. FreeRTOS is an RTOS for microcontrollers and microprocessors; Zephyr is another RTOS project architected for small, connected, and resource-constrained embedded devices.