<p>The increasing adoption of electric vehicles has highlighted the critical role of onboard chargers in facilitating efficient and convenient charging solutions. As an onboard charger (OBC) is installed inside the vehicle, the charging converter of OBC should be highly efficient, compact in size, lightweight, and inexpensive. However, selecting the most suitable AC–DC converter topology for OBCs poses a significant challenge. This paper presents an extensive review on the single-phase bidirectional isolated two-stage and single-stage onboard chargers. A comparative analysis is also performed among some selected non-resonant matrix single-stage and two-stage topologies. They are designed with identical design and operational specifications. They are compared based on the total number of components, voltage and current stress of switches, power losses, and overall efficiencies. Finally, the paper explores future research opportunities to advance the onboard charger technology further.</p>