RoundTrip — prove your export did not lie

Between "I exported it" and "it opened correctly on their machine" there is a blind spot. Materials come off. The scale arrives a hundred times too big. The second UV channel is simply not there. Bones are renamed, shape keys are gone, the animation ends up baked at the wrong step. And the person who finds out is never you — it is whoever you sent the file to, a day later.

RoundTrip closes that gap the only honest way there is: it exports what you selected, reads that file straight back into a scene of its own, and compares the two item by item.

What it compares

Objects and the names they came back under. Position, rotation and scale, with the format's own unit and axis conversion accounted for. Vertex, edge and face counts, and the vertex positions themselves — matched by proximity rather than by index, because importers reorder vertices and some formats split them along seams. Every UV channel with its name and the area it covers. Vertex colours. Material slots with their base colour, roughness, metallic and the textures they reference. Shape keys, and how far each one actually moves the mesh. Bones, their hierarchy and their rest positions. And the animation, sampled as real positions on several frames — because exporters bake curves, and a baked curve is never the same curve.

It separates loss from normal

Not every difference is a problem, and a tool that shouts at all of them teaches you to stop reading it. A format that stores only triangles will return your six-sided cube as twelve triangles; the geometry is identical and RoundTrip says so as a note. FBX writes an explicit normal for every corner: your shading survives exactly, and that is a note too. But a UV channel that did not arrive, a shape key that came back flat, a material that lost its texture — those are losses, and they are marked as losses.

Measured, not assumed

Every number in the report is computed by RoundTrip on the re-imported object, not read out of the exporter's own log. Some examples from the test suite that ships with the product: OBJ drops the second UV channel, the vertex colours and the shape keys, and those three are exactly what gets reported — nothing more. glTF returns an eight-vertex cube as twenty-three vertices and twelve triangles. USD renames the first UV channel. FBX keeps everything but does not store bone length: the joints line up to zero, while the tip of a leaf bone lands twenty-five centimetres away on a rig one and three quarter metres tall. That last one is reported as what it is — bone lengths, not a moved rig — because skinning is unaffected and frightening you about it would be a lie.

It changes nothing

The imported copy lives in a scene of its own and is removed afterwards together with every mesh, material, image and action that arrived with it. The check takes a fingerprint of your scene before and after and tells you if they differ — that verification is part of the product, not a sentence in this description.

It also checks files you already sent

Point it at an FBX, glTF, OBJ or USD file you exported last week and it compares that file with the objects you have selected now. Useful the moment somebody writes to say something is wrong on their end.

Compatibility

Blender 4.2 and later on Windows, macOS and Linux. FBX, glTF and GLB, OBJ, USD, through the importers and exporters that ship with Blender — so what it measures is what your pipeline actually gets. Measured live on 5.1 and 5.2, 87 checks green on both.

License

GPL-3.0.