OrbitSoftware
TLE (two line element) computation
Visualization
SaVi satellite constellation visualization
Online apps
NASA 3D Realtime Satellite Tracker (Java)
NORAD SGP4/SDP4 Implementations - C++/C# ports of the NORAD algorithms for Windows
SaVi satellite constellation visualization
NASA 3D Realtime Satellite Tracker (Java)
NORAD SGP4/SDP4 Implementations - C++/C# ports of the NORAD algorithms for Windows