Smartphone Based 3D Indoor Localization and Navigation During the last century navigation systems have become ubiquitous and guide drivers cyclists and pedestrians towards their desired destinations. While operating worldwide they rely on line of sight conditions towards satellites and are thus limited to outdoor areas. However finding a gate within an airport a ward within a hospital or a universitys auditorium also represent navigation problems. To provide navigation within such indoor environments new approaches are required. This thesis examines pedestrian 3D indoor localization and navigation using commodity smartphones: A desirable target platform always at hand and equipped with a multitude of sensors. The IMU (accelerometer gyroscope magnetometer) and barometer allow for pedestrian dead reckoning that is estimating relative location changes. Absolute whereabouts can be determined via Wi Fi an infrastructure present within most public buildings or by using Bluetooth Low Energy Beacons as inexpensive supplement. The buildings 3D floorplan not only enables navigation but also increases accuracy by preventing impossible movements and serves as a visual reference for the pedestrian. All aforementioned information is fused by recursive density estimation based on a particle filter. The conducted experiments cover both theoretical backgrounds and real world use cases. All discussed approaches utilize the infrastructure found within most public buildings are easy to set up and maintain. Overall this thesis results in an indoor localization and navigation system that can be easily deployed without requiring any special hardware components.