Free Online STL Editor
Resize, cut, fix holes and export STL files right in your browser. For large scans, use the desktop app for Windows, macOS and Linux.
No sign-up: the editor opens right on this page.
- Free to use and download
- Nothing to install
- Saves STL, OBJ, PLY and 3MF
Edit your STL right here
Click Open Files and pick an STL on your computer, change it with the tools on the ribbon, then click Export to download the result. No sign-up: the file is opened in your browser, not uploaded.
Try the full MeshInspector app
The editor above has the main STL editing tools and needs no account. The full app adds inspection, measurement, repair and every tool of your plan, for large scans and whole projects: open it in your browser or install it on Windows, macOS or Linux.
What you can do with your STL
The editor on this page needs no sign-up and has Scale, Transform Object, Mirror, Measure Distance, Section, Fill Holes, Hollow/Thicken, Simplify and Export. With a free account, every tool below works in the web app and in the desktop app; tools marked Makers plan need a paid plan, which you can try free for 30 days.
- Free
Resize, rotate and mirror
Scale the model by any factor, for example 25.4 to turn inches into millimetres. Turn and move it with Transform Object, or flip it with Mirror.
Scale guide - Free
Measure
Measure distances and angles on the mesh, and read its size, volume and area in the Information panel.
Measure Distance guide - Free
Cut and split
Cut the model with a plane in Section and keep one or both halves, or cut along a drawn path with Mesh Cut & Measure.
Section guide - Free
Fill holes
Close gaps in scans and broken meshes with Fill Holes, or join two openings with Stitch Two Holes.
Fill Holes guide - Free
Reduce triangles
Make heavy files lighter with Simplify by setting a target triangle count or a percentage. Remesh makes the triangles even.
Simplify guide - Free
Hollow and thicken
Make a hollow object or add wall thickness to a thin surface with Hollow/Thicken.
Hollow/Thicken guide - Free
Convert and export
Save the result as STL, OBJ, PLY or 3MF, or open OBJ, PLY, 3MF and STEP files and save them as STL.
Export guide - Makers plan
Combine and subtract
Join, intersect or subtract two models with Mesh Boolean.
Mesh Boolean guide - Makers plan
Repair in one click
Mesh Healer finds print problems such as holes, self-intersections and thin walls, and repairs holes, self-intersections, flipped triangles and stray parts in one click.
STL file repair
How to edit an STL file online in 3 steps
The same three steps work in the editor on this page, in the web app and in the desktop app.
Open your STL
In the editor on this page, click Open Files and pick an STL file on your computer; no account is needed. In the web and desktop apps, Open Files is on the Home tab, and MeshInspector also opens OBJ, PLY, 3MF, STEP and other formats.
Edit the model
Pick a tool on the ribbon and set its options in the panel. Here Simplify reduces 266,304 triangles to 66,576 when you click Apply; it is on the STL Editor tab of the editor on this page and on the Mesh Repair tab of the apps.
Export the result
Click Export and save the model as STL, OBJ, PLY or 3MF. In the browser, the file downloads to your computer, also from the editor on this page without an account.
Online or desktop
Start in the browser: the editor on this page needs no account. For every tool of your plan, sign in to the web app or install the desktop app; both use the same account.
In the browser
- Runs in a desktop browser, with nothing to install.
- The editor on this page works without an account and has the main editing tools; the web app at app.meshinspector.com has every tool of your plan.
- STL, OBJ, PLY and 3MF files are opened and saved in the browser's memory, not uploaded. STEP files are converted on our server, so they open only after you sign in.
- The browser limits the memory, so very large scans may not fit.
Desktop app
- Windows (x64 and ARM64), macOS (Intel and Apple silicon) and Linux (Ubuntu 22.04 or newer).
- Built for large meshes and 3D scans: uses your computer's memory and GPU.
- Adds AI assistants through MCP and desktop-only tools such as Python automation.
STL is a mesh, not CAD
An STL file stores only the surface of a model as triangles. It has no sketches, features or editing history, so an STL editor changes the mesh itself: it scales, cuts, joins, repairs and simplifies triangles. That covers most 3D printing fixes. To change a design precisely, for example a hole diameter for a press fit, edit the original CAD model and export a new STL.
Edit STL files with AI
The MeshInspector desktop app includes an MCP server, so AI assistants such as Claude Desktop, Claude Code and Cursor can drive it: open a model, run tools like Simplify or Fill Holes, and export the result. You need to be signed in to MeshInspector; when you are signed out, the AI tools are switched off.
MCP setup guideSTL editor FAQ
Is there a free online STL editor?
Yes. The editor on this page is free and needs no sign-up: open an STL, then scale, move and rotate, mirror, measure, cut with Section, fill holes, hollow or simplify it, and export to STL, OBJ, PLY or 3MF. The free Community plan adds tools such as Remesh; Mesh Boolean and Mesh Healer are in the paid Makers plan.
How can I edit my STL file?
Open the file in the editor on this page and pick a tool on the ribbon: Scale to resize, Section to cut, Fill Holes to close gaps or Simplify to reduce triangles. Set its options in the panel and run it, then click Export to save the model as STL or another format.
Is it possible to edit an STL file?
Yes, as a mesh. An STL file stores triangles only, without the sketches and features of a CAD model, so you change the geometry directly: resize, rotate, cut, fill holes or reduce triangles. For a precise design change, such as a new hole diameter, edit the CAD source and export a new STL.
What is the easiest tool to modify an STL file?
For common changes, one tool does the job: Scale changes the size, Transform Object rotates and moves the model, Section cuts it along a plane, and Fill Holes closes gaps. Each tool opens a small panel with its settings, so you do not need to learn 3D modeling first.
Is there a free online tool that can fix STL files?
Yes. Fill Holes in the editor on this page closes gaps without sign-up. The free Community plan adds Stitch Two Holes, which bridges two openings, and Remesh, which makes triangle sizes even. For automatic checks of print problems and one-click repair of holes, self-intersections and stray parts, use Mesh Healer in the Makers plan.
How do I edit text on an STL file?
Text in an STL file is geometry, not editable text, so it cannot be retyped. To change a label, edit the source CAD file. In MeshInspector you can add new lettering: Create Text builds text as a separate mesh in any plan, and Text on Mesh embosses or engraves text on the surface in the Makers plan.
Can AI edit an STL file?
Yes, with the MeshInspector desktop app. Its built-in MCP server lets AI assistants such as Claude Desktop, Claude Code or Cursor open a model, run tools like Simplify or Fill Holes, and export the result. You must be signed in to MeshInspector while the assistant works. The MCP setup guide in our knowledge base shows how to connect it.
Do I need to install anything to edit STL files?
No. The editor on this page runs in a desktop browser, with nothing to install and no sign-up. Install the desktop app for Windows, macOS or Linux when you work with large files or 3D scans, or when you want AI assistants such as Claude Desktop or Cursor to control MeshInspector through MCP.
