  We put forward a functional renormalisation group approach for the direct
computation of real time correlation functions, also applicable at finite
temperature and density. We construct a general class of regulators that
preserve the space-time symmetries, and allows the computation of correlation
functions at complex frequencies. This includes both imaginary time and real
time, and allows in particular the use of the plethora of imaginary time
results for the computation of real time correlation functions. We also discuss
real time computation on the Keldysh contour with general spatial momentum
regulators. Both set-ups give access to the general momentum and frequency
dependence of correlation functions.
