See What Changed Between Two 3D Models

TL;DR: 3D Model Compare is a free online tool that shows the differences between two 3D models — a deviation heatmap, the exact added and removed material, even G-code layer diffs — right in your browser, no signup, nothing uploaded or transferred.Great for checking a revised STL before printing, two exports of a CAD part, or what a slicer changed between project versions.

Start Comparing Models…
Screenshot of 3D Model Compare
Christopher Atlan

Built by Christopher Atlan at Leitmotif GmbH. Making file-comparison tools since 2020 — building software for over 18 years. diff.tools is one idea: a focused tool for each format, with results you can hand from one tool to the next.

A quick tour

  1. Every deviation, measured and mapped

    Drop two models and read the differences as a signed deviation heatmap — histogram legend, tolerance band, and a probe: click anywhere on the model to pin the exact millimeter value. Changed regions are listed so you can step through them one by one.

    Two revisions of a mounting plate compared as a deviation heatmap, with summary, stats, and changed regions in a sidebar
    Two revisions of a mounting plate — the moved boss glows, the rest stays gray.

  2. The exact added and removed material

    Not an approximation: solid boolean intersections compute the real difference volumes — removed material in red, added in blue, with their exact cubic millimeters. GitHub shipped 3D diffs in 2013 and abandoned them; this is that idea, finished.

    The exact-changes view: the removed boss as a red solid and the added boss as a blue solid on a ghosted plate

  3. G-code, layer by layer

    Compare two sliced files — plain G-code or .gcode.3mf exports — and scrub a synced layer slider with a change strip that marks exactly which layers differ. Only the changed toolpath segments are colored, and the print settings from the config blocks are diffed alongside.

    A G-code comparison on a changed layer: added toolpath segments in blue, a per-layer change strip, and a changed-layers list

  4. Slicer projects are first-class

    Bambu Studio and PrusaSlicer project 3MFs open directly, and their slicer settings are diffed side by side — layer height, infill, filament. And when the geometry didn't change at all, the verdict says so instantly: no hunting for phantom differences between two re-exports.

    Two Bambu project files side by side: an instant identical-geometry verdict plus a slicer-settings diff showing changed layer height, infill, and filament

  5. Six ways to look at it

    Lockstep two-up, a blink comparator, split with a swipe divider, emphasis overlay, the heatmap, and the exact changes — whichever view answers your question. Alignment is handled too: presets, an ICP “refine” step for scanned or re-exported parts, and per-part alignment for rearranged build plates.

How to compare two 3D models?

  1. Open the free 3D model comparison tool in any modern browser — it runs on your device, no signup.

    Start Comparing…

  2. Click Choose Model A and pick the first file, then Choose Model B for the other one. STL, OBJ, 3MF, STEP, and G-code are all fine — even mixed. The comparison starts automatically.

  3. Read the verdict: identical geometry is called out instantly; otherwise explore the deviation heatmap, step through the changed regions, or switch to the exact added/removed solids. For G-code, scrub the layer slider.

Frequently asked questions

  1. Can I compare two STL files for differences?

    Yes — drop two files and read the result three ways: a deviation heatmap, discrete changed regions you can step through, and the exact added and removed material computed with solid booleans. STL, OBJ, 3MF, STEP, and G-code all work.

  2. Can I diff sliced G-code or .gcode.3mf files?

    Yes. Layers are matched and compared: a synced layer slider, a per-layer change strip, and only the changed segments colored. The print settings from the config blocks are diffed too.

  3. Does it open Bambu Studio or PrusaSlicer project files?

    Yes. 3MF project files with production extensions open fine, and the slicer settings of two projects are compared side by side — layer height, infill, filament, and everything else that changed.

  4. Can it tell me two exports are identical?

    Yes — instantly. Re-exports of the same part (reordered triangles, binary vs ASCII) get an “identical geometry” verdict without any heavy computation.

  5. Are my files uploaded?

    No. The comparison runs entirely in your browser; file contents never leave your device.

  6. Can it repair or edit my models?

    No — it’s deliberately a viewer. It shows you the differences; it never touches your files.

  7. How are the models compared?

    The meshes are aligned (with an optional ICP refine step, and per-part alignment for rearranged plates), sampled against each other for signed deviations — that’s the heatmap — and intersected with exact solid booleans for the added/removed view. The tolerance is yours to set; the default is 0.05 mm.

  8. Which browsers are supported?

    Any current browser — Chrome, Edge, Safari, or Firefox. Files up to 256 MB per side.

Requirements

Any current browser — Chrome, Edge, Safari, or Firefox. Files up to 256 MB per side.

Privacy & Data Processing

Privacy and security aren't just something you should hope for — they're something you should expect. Modern browsers allow us to process everything directly on your device, which means we never upload, transfer, or share your files.

Your files stay completely private. All comparisons happen locally in your browser. Your data stays your business.

LeitmotifChristopher Atlan
+2

The team behind the tool

We're Leitmotif, a small company from the Alps — Carinthia, Austria and Bavaria, Germany. File comparison is what we do all day: we make Kaleidoscope, the Mac diff app, and diff.tools brings that experience to the browser.

We believe professional tools should be beautiful to look at and fun to use, while giving you all the power you need to get the job done. And we respect your files too much to ever upload them — everything here runs on your machine.

Feedback

We're constantly improving our free online 3D model comparison to make it faster and more accurate. Share your feedback and help us understand what kind of models you compare.

Share this page

FacebookLinkedInRedditLINETelegramWhatsApp