Chimera is a userspace sandbox for code that doesn't fully trust, allowing it to run arbitrary, generated commands on a machine without compromising system security. It confines processes to their actions on the host while still granting access to host files and tools. Chimera achieves this through same-ISA dynamic binary translation and system call interception, running as an ordinary program without requiring a VM, container, or special privileges. It supports Linux/x86 and has a work-in-progress port to Darwin/arm64, and can be installed via cargo. The sandbox can be used to run untrusted code from the command line or embedded in a program, with embedders specifying a system-call handler to decide how each guest syscall is handled.