We present the principle of an electrostatically actuated cantilever device that can calibrate the cantilever stiffness on-chip with uncertainties in the range of 5%. The calibration procedure is quick, simple and non-destructive. The device can be fabricated using routine micromachining techniques and be easily made compatible with commercially available atomic force microscopes (AFMs). The electrostatic actuation makes the device quite versatile. In addition to the usual AFM-like applications, the device can also be used for mass-sensing applications as well as an effective interfacial force microscope.