Our Rayfract seismic refraction tomography software allows reliable imaging of subsurface velocity structure including faults, strong lateral velocity variation and other velocity anomalies. Our Smooth inversion tomographic method is based on physically meaningful modeling of seismic first break energy refraction, Transmission and diffraction. Both P-wave and S-wave propagation is modeled with wave paths (also known as Fresnel volumes) instead of conventional seismic rays. This increases the numerical robustness of the method. A smooth initial 1D gradient model is determined automatically directly from the traveltime data, by averaging DELTA-t-V method 1D velocity-depth Profiles along the seismic line. This procedure delivers reliable smoothed models even in case of velocity inversions. The initial model is then refined with true 2D WET Wavepath Eikonal Traveltime tomography. No need to map traveltimes to refractors. Supports many input data formats and extreme topography. Also allows interpretation of traveltimes with conventional Plus-Minus and Wavefront seismic refraction methods. Now supports crosshole surveys and walkaway VSP surveys.