  Many experiments in atomic and molecular physics require simultaneous
frequency stabilization of multiple lasers. We present a stabilization scheme
based on a scanning transfer cavity lock that is simple, stable and easily
scalable to many lasers at minimal cost. The scheme is based on the Red Pitaya
STEMlab platform, with custom software developed and implemented to achieve up
to 100 Hz bandwidth. As an example demonstration, we realize simultaneous
stabilization of up to four lasers and a reduction of long-term drifts to well
below 1 MHz per hour. This meets typical requirements, e.g. for experiments on
laser cooling of molecules.
