STLPal
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Online STL editor

Resize, rotate, mirror and combine STL files right here. No install, and the file stays on your computer.

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Good to know

GuideWhat is an STL file?An STL file is a 3D shape made of triangles.

What you can do here

  • Set an exact size. Type 120 in Z (height) and the part scales to 120 mm tall. With Lock proportions on, nothing gets stretched.
  • Fix the wrong unit. A model that comes in 25 times too small was probably saved in inches; click Inches → mm. Ten times too small usually means centimetres.
  • Turn it 90° at a time, or mirror it. Mirroring is handy for left and right versions of the same bracket.
  • Put several files on one plate. Each part sits on the bed, and Tidy up the bed lines them up with a 5 mm gap.
  • Save as STL (everything in one mesh) or 3MF (each part stays its own object, in millimetres).

When to use a CAD app instead

This editor moves, sizes and combines whole parts. It doesn't cut, drill holes, add text or change the shape itself.

For those, Tinkercad is free and runs in the browser. Fusion and Onshape are stronger if you design parts often. Most slicers can also cut a model in two with a cut tool.

How it works

  1. 1Drop one or more STL, 3MF or OBJ files in the box.
  2. 2Pick a part. Set its size in mm, rotate it 90° at a time, or mirror it.
  3. 3Hit Lay flat to put it on the bed, then download STL or 3MF.

Questions people ask

Checked October 2026

Do my files get uploaded?
No. Everything runs in your browser. The file never leaves your computer, so it works for client files and unreleased designs too.
Can I change the actual shape, like cut or add holes?
Not here. This editor moves, sizes and combines whole parts. For cutting and holes, a free CAD app like Tinkercad or your slicer's cut tool works better.
How do I make it an exact size?
Type the width, depth or height in millimetres. Keep "Lock proportions" on and the other two follow, so nothing gets stretched.
Why save as 3MF instead of STL?
3MF keeps each part separate and records that the units are millimetres. Bambu Studio, PrusaSlicer, OrcaSlicer and Cura all open it.

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