Main Street Autonomy makes sensor calibration, localization, and mapping software that improves robot performance and expands operational domain. Our solutions use any combination of sensors, are easy to configure and simple to use, operate indoors and outdoors, and deliver industry-leading accuracy. MSA resiliently handles intermittent or unreliable sensors, which enables transitions to/from GPS-denied areas. We operate in environments ranging from flat low-feature to complex 3D terrain with bumps, slopes, camber, and associated uneven sensor sightlines. We perform true multi-modal sensor fusion in challenging egomotion situations without synchronized sensors.