A scan driver circuit includes a pull-up unit and a bootstrap unit arranged on a base. The pull-up unit includes a pull-up thin-film transistor for supplying a scan drive signal. The bootstrap unit includes a bootstrap capacitor electrically connected with the pull-up thin-film transistor. The pull-up thin-film transistor includes a gate electrode, a first insulation layer, and a source electrode and a drain electrode stacked in sequence from the base. The bootstrap capacitor includes first and conductive electrodes. The first conductive electrode and the source electrode are arranged on the same layer and are electrically connected together. A second insulation layer is arranged between the second conductive electrode and the second electrode. The second conductive electrode is electrically connected, through a first via that extends through the second insulation layer and the first insulation layer, to the gate electrode. An array substrate and a display device are also provided.