Semiconsoft, Inc. is a privately held company with headquarters in Southborough, Massachusetts. It was founded in 2001 with the mission to provide thin-film analysis software and services for semiconductor R&D and production. TFCompanion software was introduced in 2002. We continue active development of TFCompanion and constantly adding new features and capabilities. It is recognized as a leading thin-film data analysis software. One of the challenges of optical metrology, as an indirect measurement technique, is the selection of measurement methods and conditions to achieve optimal precision on specific application: this problem is faced by metrology manufacturers, production users or researchers alike. In 2004 we have introduced an ErrorEstimator module that allows to estimate accurately the measurement precision depending on measurement condition, application and technique.