An applicator for aligning a screen protector on a portable electronic device (D) with a screen, four edges and a rear face opposite to the screen. The applicator comprises a body with an engagement member (2, 11) and an alignment feature (3, 5, 12, 13). The engagement member (2, 11) is arranged for edgewise engagement with no more than three of the four edges of the device (D) to align the applicator with the device by movement in a direction generally parallel to the plane of the screen such that the alignment feature (3, 5, 12, 13) covers a portion of the face of the device comprising the screen which is not covered by the screen protector allowing an edge of the screen protector to be located with respect to the alignment feature.