The strength of multi-messenger astronomy comes from its capability to increase the significance of a detection through the combined observation of events coincident in space and time. This is particularly valuable for transient events, since the use of a narrow time window can allow a reduction of background of the search.
In KM3NeT, we are actively monitoring and analysing a variety of external triggers in real-time, including alerts like IceCube neutrinos, HAWC gamma-ray transients, LIGO-Virgo-KAGRA gravitational waves, SNEWS neutrino alerts, and others.
In this contribution, we present the follow-up of various external alerts using the complementary capabilities of the two KM3NeT detectors, ORCA (covering the few GeV to few TeV energy range) and ARCA (ranging from sub-TeV energies up to tens of PeV). Both detectors were collecting high-quality data with partial configurations during the period of the studied alerts, which goes from December 2021 until June 2023.