Widely tunable and narrow-linewidth lasers at visible wavelengths are necessary for applications such as quantum optics, optical clocks and atomic and molecular physics. At present, the lasers are benchtop systems, which precludes these technologies from being used outside research laboratories. Here we demonstrate a chip-scale visible laser platform that enables tunable and narrow-linewidth lasers from near-ultraviolet to near-infrared wavelengths. Using micrometre-scale silicon nitride resonators and commercial Fabry–Pérot laser diodes, we achieve coarse tuning up to 12.5 nm and mode-hop-free fine tuning up to 33.9 GHz with intrinsic linewidths down to a few kilohertz. In addition, we show fine-tuning speeds of up to 267 GHz µs −1 , fibre-coupled powers of up to 10 mW and typical side-mode suppression ratios above 35 dB. These specifications of our chip-scale lasers have only been achieved previously using large state-of-the-art benchtop laser systems, making our lasers stand out as powerful tools for the next generation of visible-light technologies.