# ScanRuler: browser-based 3D metrology for your scans

- Link: https://opensourcecad.nl/en/scanruler-browser-based-3d-metrology/
- Published: 2026-11-02T11:47:46+01:00
- Author: Marijn van den Heuvel \+ AI

_This is the English reading version of the Dutch news item [ScanRuler: browser-gebaseerde 3D-metrologie voor je scans](https://opensourcecad.nl/nieuwe-cad-apps/scanruler-browser-gebaseerde-3d-metrologie/)._

ScanRuler is a free, open-source web application by CNC Kitchen for measuring and
comparing 3D scans. It runs entirely in the browser at [scanruler.com](https://scanruler.com/),
with no installation required and your files never leaving your computer.

[⌊ScanRuler in the browser: a distance of 99.149 mm measured between two points 
on a bracket.⌉⌊ScanRuler in the browser: a distance of 99.149 mm measured between
two points on a bracket.⌉[

A distance of 99.149 mm measured between two points on a bracket.

## What ScanRuler does

The tool has three workspaces that share the same loaded scan:

 * **3D Measure**: automatically fit spheres, cylinders, and planes to selected 
   points on your scan. Build measurement points, lines, and planes from them, and
   extract distances and angles between them. You can also check tolerances (flatness,
   parallelism, coaxiality) and align the scan via a 3-2-1 alignment. Results can
   be exported as STEP files.
 * **Deviation**: color a deviation map over your scan. You can see how far the 
   part deviates from the nominal CAD model (load a mesh or STEP file) or from a
   single fitted element: is this plane flat, is this hole round? The map can be
   played as an animation, scaled, and looped so you can see which direction the
   part has deformed.
 * **Thickness**: measure the wall thickness of the part itself, without a reference
   model and without alignment. Just load one file and measure.

## Practical details

ScanRuler accepts STL, PLY, and OBJ files (meshes only) for scans. STLs have no 
units, so you are asked what the unit is (mm, cm, m, inch) when opening. PLY and
OBJ are read in millimeters. Reference CAD models in the Deviation workspace also
accept STEP files.

Everything runs locally in your browser — your scan files are never sent to a server.
There is an undo/redo system that works across all workspaces (Ctrl+Z / Cmd+Z). 
For new users there is a step-by-step hint that stops showing after two visits.

Projects are saved as a single .scanruler file (a zip containing the scan, the reference
model, and a project.json with all measurements, alignments, and settings). Additionally,
changes are saved locally every two seconds as a recovery point in this browser.

## My verdict

ScanRuler is an original program, not a copycat “vibecoded” app like so many others.
I tested it in the browser myself, and you can immediately see that real work went
into it. The downside is that the interface feels clunky and it takes considerable
effort to actually get anything done with it. Tools like this prove again that FreeCAD
add-ons or workbenches become less interesting to build: you can easily build a 
standalone app yourself, [as we wrote earlier](https://opensourcecad.nl/freecad/de-freecad-plaag-als-niemand-luistert-doe-ik-het-zelf-maar/).
Keep an eye on this site for updates and tests.