Abstract:GNSSs are widely used in engineering solutions that demand high accuracy. In areas requiring decimeter precision, Internet online post-processing services are a potential tool for developing GNSS observations. These services have been contributed by a number of organizations, providing users simple, unlimited, and (above all) free access. As a result, online services could be an alternative to complex and expensive commercial programs. Authors analyzed free public online GNSS services for post-processing kinematic 5-second observations in PPP mode with accuracy estimation.