  We introduce version 2.0 of $Z'$-explorer, a software tool which provides a
simple, fast and user-friendly test of models with an extra $U(1)$ gauge boson
($Z'$) against experimental LHC results. The main novelty of the second version
is the inclusion of missing energy searches, as the first version only included
final states into SM particles. Hence $Z'$-explorer 2.0 is able to test dark
matter models where the $Z'$ acts as an s-channel mediator between the Standard
Model and the dark sector, a widespread benchmark employed by the ATLAS and CMS
experimental collaborations. To this end, we perform here the first public
reinterpretation of the most recent ATLAS mono-jet search with 139 fb$^{-1}$.
In addition, the corresponding searches in the visible final states have also
been updated. We illustrate the power of our code by re-obtaining public plots,
and also showing novel results. In particular, we study the cases where the
$Z'$ couples strongly to top quarks (top-philic), where dark matter couples
with a mixture of vector and axial-vector couplings, and also perform a scan in
the parameter space of a string inspired St\"uckelberg model. $Z'$-explorer 2.0
is publicly available on GitHub.
