Users looking for stp to stl conversion are usually interested in export of 3D models for 3D printing purposes - stereo lithography. Models in ISO STEP product data files (.stp, .step files) and STL format (.stl files) for 3D printing are usually well-supported in modern 3D modeling tools, so many should offer you tools for export stp to stl for 3d printing.
Open STP file Open STL file3D viewer and converter with huge file type support
A website STL converter
A Mac version of the popular 3D visualisation software
A set of 3D modeling tools
A converter for 3D formats
An online CAD conversion service
Creo Parametric (formerly known as Pro/ENGINEER) is a complete 3D CAD software solution by PTC
A CAD converter with huge format support
A CAD visualizaton, analyzation and translating system
An open source multiplatform 3D CAD/MCAD/CAx/CAE/PLM modeler
A commercial online CAD converter
A 3D CAD translation software
A dedicated CAD converter