Magnetic field mapping is tedious; a magnetometer probe collects magnetic field data in a point-by-point manner within a two-dimensional (2D) or three-dimensional (3D) space. Magnetometer arrays accelerate this process by replacing point-by-point mapping with plane-by-plane mapping. When mapping a large space, a motorized stage is additionally required; the limitations include power inefficiencies, large footprints, cost, and the absence of real-time data acquisition. Here, we introduce MagMaps, a modular Lego-like approach to magnetic field mapping that overcomes the limitations described above. MagMaps includes a set of physically identical modules termed “MagBricks” that can be stacked in all three axes (similar to Lego bricks); this covers the region of interest and eliminates the need for a motorized stage. Each MagBrick is an independent enslaved module with a unique address, having a microcontroller that continuously acquires magnetic field data from a magnetometer array. An additional brick termed the “MasterBrick” serves as a bridge between the computer and the MagBricks. The MasterBrick collects magnetic field data from uniquely addressed MagBricks and communicates them to a computer, where they are sorted and displayed in real-time. This modular Lego-like approach and the use of only off-the-shelf electronic components allows MagMaps to offer real-time magnetic field mapping that is portable, power-efficient, and economical for various 2D or 3D spaces. IEEE