  We present lenscat, a public and community-contributed catalog of strong
gravitational lenses found by electromagnetic surveys. The main objective of
lenscat is to compile a simple, easy-to-access catalog that can be used in a
variety of lensing studies, such as facilitating the search for the host galaxy
of a candidate strongly lensed transient event. We also provide a python
package to interact with tools commonly used by the community. This allows end
users both with and without lensing expertise to obtain a list of known strong
lenses within a given search area, and to also rank them by their respective
searched probabilities. Here, we exemplify this by crossmatching the
gravitational wave joint sky localization region of an interesting pair of
events GW170104-GW170814. Other examples with short gamma-ray bursts are given.
Thanks to the open and simple infrastructure of lenscat, members of the lensing
community can directly add newly found lenses from their own studies to help
create a long-lasting catalog that is as exhaustive and accessible as possible.
