  In this review we aim to describe the most stringent tests of the strong
equivalence principle, the fundamental principle of General Relativity, using
pulsar timing. For this purpose, we first construct the parametrized
post-Newtonian and post-Keplerian formalism together with their parameters.
Then we constrain the post-Newtonian parameters associated to the violation of
the strong equivalence principle with the most stringent tests using pulsar
timing techniques. We will in particular see that these bounds are the most
constraining limits on a violation of the principle. Finally we will discuss
the implication of these results on scalar-tensor theories as well as massive
gravity. We will find that the set of possible scalar-tensor theories can be
tightly reduce, however in the case of massive gravity, the level of precision
is not sufficient to probe the predicted mass of the graviton.
