OGLE-2017-BLG-1434L is a Sun-like G-type star (about 0.23 solar masses, 5,778 K), 860 light-years from Earth. OGLE-2017-BLG-1434L b is a 4.4-Earth-mass planet, at 1.180 AU from its star, discovered in 2018 via microlensing. Microlensing detections occur when a foreground star's gravity briefly magnifies a background source, revealing planets that are otherwise too faint and distant to observe directly. OGLE-2017-BLG-1434L b orbits at roughly the distance of Mars from the Sun. Its low mass makes OGLE-2017-BLG-1434L b a Neptune- or super-Earth-class world rather than a gas giant.