Flavour physics observables are excellent probes of new physics up to very
high energy scales. Here we present FlavBit, the dedicated flavour physics
module of the global-fitting package GAMBIT. FlavBit includes custom
implementations of various likelihood routines for a wide range of flavour
observables, including detailed uncertainties and correlations associated with
LHCb measurements of rare, leptonic and semileptonic decays of B and D mesons,
kaons and pions. It provides a generalised interface to external theory codes
such as SuperIso, allowing users to calculate flavour observables in and beyond
the Standard Model, and then test them in detail against all relevant
experimental data. We describe FlavBit and its constituent physics in some
detail, then give examples from supersymmetry and effective field theory
illustrating how it can be used both as a standalone library for flavour
physics, and within GAMBIT.