This research presents techniques suitable for pedestrian localization in closed environments using mobile devices without the need of GPS technology. The objective of this research is to design and implement a pedestrian localization system, which can be used directly without investments into building a support infrastructure and acquiring expensive devices. The research problem is that GPS signal is weak or absent in closed spaces, thus cannot be used to identify location. Several technologies, which are using mobile sensors, are used as part of the experimental methodology to implement the system. These include tracking of wireless networks, dead reckoning, step detection, and barcode scanning. These technologies were combined and coded in the Java programming language to form the localization system. Beside the technologies mentioned above, crowdsourcing is used for gathering environment data needed for calculation of location estimates. Currently, the implementation has been done for the Android platform, but it is designed to be universal, and can be expanded to other mobile platforms. Preliminary results of the prototype application report a positioning error (standard deviation) of roughly 2 meters.