Linux system call tracing and injection API Tracy is a library that offers cross platform event-based system call tracing and injection; fast memory access as well a few other neat features using ptrace. (Currently only with the Linux kernel) Tracy currently offers event-based system call tracing and (system call) injection on the ARM, x86 and AMD64 Linux-targets using the ptrace system call. Support for other kernels and architectures (mostly: *BSD) is planned. The aim of the project is to offer a uniform system call tracing (and injection) API on the popular UNIX platforms. Tracy can be used to create transparent (network) proxies, fault injection tests, secure user space jails and system call debuggers. The talk will discuss the implementation of Tracy and future plans with regard to new features, stability, and feasibility of cross platform tracing/injection code.