InStep

InStep is a comprehensive software solution designed mainly to convert STL, OBJ, DAE, VRML, X3D or GDML files to STEP format, while also offering a set of error correcting tools.
The program is quite advanced, so if you are not used to working with similar applications, it might take you a while before you can get accustomed to using it properly.
Nonetheless, after importing the files you want to work with, you can zoom in and out, or change the angle of the object, so as to view it from several different perspectives. For the same purpose, you can use the buttons in the toolbar, and display the object from a specific view point ('Top', 'Front', 'Back', 'Isometric'). Additionally, you can grab a snapshot of the current image and export it to PNG, JPG, BMP or GIF files.
Aside from its conversion abilities, InStep provides you with various other tools, namely 'Combine Planar Features' or 'Degeneracy Check'. Moreover, you can 'Align' or 'Flip Normal Vectors', 'Inflate Thin Mesh to Create a Thin Solid', as well as 'Attempt to Patch Holes Where Edges Are Open'.
InStep allows you to 'Extract CAD Surfaces from Volume Meshes', or 'Create Shell Meshes from CAD Mesh', all these using the buttons available in the program's toolbar. You can also 'Display Statistics About the Volume Mesh' or 'Generate Prismatic Elements from Shell Elements'.
The 'Tools' offered by InStep let you compress or de-compress STP files, using the 'Modify Existing STP Files' options. Additionally, you can customize the 'Import / Export' settings, as well as the 'Numerics' preferences, or the '3D Motion Settings'. Also, you can create 'Custom Light Sources'.
To conclude, InStep is a professional utility developed for engineers as well as students in the field, meant to assist them in converting their files to formats supported by other applications.