  We investigate source and detector non-standard neutrino interactions at the
proposed ESS$\nu$SB experiment. We analyze the effect of non-standard physics
at the probability level, the event-rate level and by a full computation of the
ESS$\nu$SB setup. We find that the precision measurement of the leptonic mixing
angle $\theta_{23}$ at ESS$\nu$SB is robust in the presence of non-standard
interactions, whereas that of the leptonic CP-violating phase $\delta$ is
worsened at most by a factor of two. We compute sensitivities to all the
relevant source and decector non-standard interaction parameters and find that
the sensitivities to the parameters $\varepsilon^s_{\mu e}$ and
$\varepsilon^d_{\mu e}$ are comparable to the existing limits in a realistic
scenario, while they improve by a factor of two in an optimistic scenario.
Finally, we show that the absence of a near detector compromises the
sensitivity of ESS$\nu$SB to non-standard interactions.
