The prototype operation of an ultrafast write–readout–erase–readout cycle of an all-optical system based on photochromic indolylfulgides is demonstrated. In the employed dye the molecular structure is switched using light of different wavelengths between two thermally stable states to allow binary encoding of information. Non-destructive readout of the bit states using infrared light completes the scheme of an all-optical memory. For ultrafast operation femtosecond light pulses are applied and it is demonstrated that two consecutive write/erase processes separated by less than 4 ps still allow the defined readout of the bit state. The short time between the write/erase and readout actions demonstrates that an all-optical data storage system based on indolylfulgides may be operated at memory clock rates that exceed 250 GHz.