Gamma-ray narrow-line Seyfert 1 galaxies ($\gamma$-NLS1) are a well-established sub-class of jetted active galactic nuclei. Their number increased systematically since their discovery in 2009, but they were usually observed as a response to flares in the gamma-ray energy band. We performed, therefore, once-a-week, year-based Swift monitoring campaigns on four prominent $\gamma$-NLS1 which include the best candidates for detection by the Cherenkov Telescope Array Observatory, namely SBS 0846$+$513, PMN J0948$+$0022, PKS 1502$+$036, and FBQS J1644.9$+$2619, in order to investigate the long-term behaviour of such kind of sources. The novelty of these campaigns is that they are unbiased with respect to possible target-of-opportunity observations, which makes our study the first on $\gamma$-NLS1 objects based on this systematic approach, and it allows us to investigate their intrinsic variability properties. We present the long-term monitoring light-curves of our objects obtained following our unbiased data acquisition strategy. We also present the recent results on the radio loud $\gamma$-NLS1 SDSS J164100.10$+$345452.7 that we monitored for two years with Swift and which we caught in flare.

Gamma-ray narrow-line Seyfert galaxies: first long-term optical, UV, and X-ray monitoring