.amf
AMF modelAdditive Manufacturing File Format
An XML format for 3D printing, published by ASTM in 2011 and later adopted by ISO. It adds curved triangles, colours, materials and lattices to the plain mesh idea of STL.
Multi-material and colour 3D prints in slicers that support it.
Opens in PrusaSlicer, Slic3r
About AMF files.obj
OBJ modelWavefront OBJ
A plain-text geometry format from Wavefront Technologies, dating from the 1980s. It lists vertices, texture coordinates, normals and faces; materials live in a companion .mtl file.
Moving static meshes between almost any 3D programs.
Opens in Blender, Maya, Cinema 4D, Windows 3D Viewer, Quick Look on Mac
About OBJ files