The possibility that the Higgs boson is a composite scalar is still open. In models that enjoy an underlying description in terms of a fundamental gauge-fermion dynamics, light scalars at the electroweak scale are predicted. Their properties can also be calculated starting from the underlying models. This leaves us with a predictive and controllable framework that can be tested at the LHC and at future colliders. I will present the most interesting and characteristic channels, which provide new standard candles to search for signs of compositeness in the electroweak sector. One of them is a singlet pseudo-scalar, associated to a U(1) global symmetry, that decays into a pair of gauge boson via anomalies, or a pair of fermions. I will show how an open window in the mass range 14 to 65 GeV can be closed by searching for boosted di-tau systems.