STL Repair Tools: A Landscape Overview

When your slicer reports that an STL file is broken, you have several options for fixing it. The most commonly mentioned tools are Meshmixer, Netfabb Basic, Windows 3D Builder, and MeshLab. Each has its strengths and limitations. JustFixSTL offers a fundamentally different approach: browser-based repair with no software to install and no files leaving your computer.

Here is how they compare.

Comparison Table

Feature	JustFixSTL	Meshmixer	Netfabb Basic	3D Builder	MeshLab
Price	Free	Free	Free (limited) / Paid	Free	Free / Open Source
Install required	No	Yes (Windows/Mac)	Yes (Windows/Mac)	Yes (Windows only)	Yes (Windows/Mac/Linux)
Platform	Any browser	Windows, Mac	Windows, Mac	Windows only	Windows, Mac, Linux
Auto repair	Yes — one click	Yes (Inspector tool)	Yes	Yes (on import)	Partial (manual filters)
Manual editing	No	Yes — full sculpting	Limited	Basic	Yes — mesh filters
Mesh analysis	Yes — detailed metrics	Basic (Inspector)	Yes	Minimal	Yes — extensive filters
Privacy	100% local — no upload	Local	Cloud features optional	Local	Local
Speed to first repair	Seconds (no setup)	Minutes (download + install)	Minutes (download + account)	Minutes (Windows update)	Minutes (download + learn UI)
Actively maintained	Yes	Discontinued (2021)	Yes (Autodesk)	Uncertain	Yes (open source)

Detailed Tool Comparisons

JustFixSTL vs. Meshmixer

Meshmixer was Autodesk's free mesh editing tool, widely recommended in the 3D printing community for its "Inspector" tool that automatically detects and fixes mesh errors. It also offered sculpting, boolean operations, support generation, and hollowing.

However, Meshmixer was discontinued in 2021. It is no longer updated, does not receive bug fixes, and may not work correctly on newer operating systems. Download links are increasingly difficult to find, and there is no guarantee the software will remain functional.

When JustFixSTL wins: When you need a quick automatic repair without installing discontinued software. When you are on Linux or a Chromebook. When you want a tool that is actively maintained.

When Meshmixer was better: When you needed manual mesh editing — sculpting, cutting, remeshing. Meshmixer's manual tools had no browser-based equivalent.

JustFixSTL vs. Netfabb Basic

Netfabb (now part of Autodesk's Fusion 360 ecosystem) is a professional mesh repair tool. The free "Basic" version has been renamed and bundled with Fusion 360, requiring an Autodesk account and a significant install. The paid version is an industrial-grade tool for additive manufacturing preparation.

When JustFixSTL wins: When you do not want to create an Autodesk account, install Fusion 360, and navigate a complex UI just to fix one STL file. When you need a quick repair on any device.

When Netfabb is better: When you need industrial features like build platform preparation, lattice generation, slicing for SLA/SLS, or batch processing of many files for production.

JustFixSTL vs. Windows 3D Builder

Windows 3D Builder is a basic 3D viewing and editing tool that comes with Windows 10 and 11. It automatically repairs meshes on import, which is convenient but opaque — you do not know what it changed or why.

When JustFixSTL wins: When you want to see what is wrong with your mesh before fixing it. When you are not on Windows. When 3D Builder's silent repair produces unexpected results (it sometimes simplifies geometry or changes dimensions).

When 3D Builder is better: If you are already on Windows and want basic mesh editing (cutting, combining, resizing) in addition to repair.

JustFixSTL vs. MeshLab

MeshLab is a powerful open-source mesh processing tool with hundreds of filters for mesh analysis, repair, simplification, and transformation. It is the Swiss Army knife of mesh processing.

When JustFixSTL wins: When you want a simple, focused experience. MeshLab's interface can be overwhelming for users who just want to fix a broken STL. Finding the right combination of filters to repair a mesh requires mesh processing knowledge. JustFixSTL does it in one click.

When MeshLab is better: When you need advanced mesh processing — Poisson surface reconstruction from point clouds, mesh simplification with specific algorithms, scripting, or processing meshes with millions of faces.

The real advantage of browser-based repair: Zero friction. You do not download software, create accounts, learn new interfaces, or worry about compatibility. Open the page, drop your file, click repair, download the fixed mesh. Done.

Advantages of Browser-Based STL Repair

JustFixSTL's browser-based approach offers several unique advantages that desktop tools cannot match:

No Installation

There is nothing to download or install. The tool runs in your web browser using WebAssembly. This means you can repair an STL from any computer — your desktop, a library computer, a Chromebook, a tablet, even your phone in a pinch.

Cross-Platform

Windows, Mac, Linux, ChromeOS — if it runs a modern web browser, it runs JustFixSTL. No need to find a platform-specific build or worry about dependency issues.

Always Up to Date

You always use the latest version. No update prompts, no version mismatches, no "this version is no longer supported" messages. The tool improves transparently.

Complete Privacy

Your STL file never leaves your computer. The entire repair process happens locally in your browser using WebAssembly. There is no server upload, no cloud processing, and no data collection. This matters if you are working with proprietary designs, pre-release products, or confidential engineering files.

Fast

No software startup time, no project loading, no navigating menus. Drop your file, see the analysis, click repair, download. The entire process takes seconds for typical STL files.

When You Might Need a Desktop Tool

Browser-based repair handles the vast majority of everyday STL fixes, but there are scenarios where a desktop tool is the better choice:

Very large files — meshes with millions of faces may exceed browser memory limits. Desktop tools can handle larger datasets by using system memory and GPU acceleration more effectively.
Manual editing — if you need to cut, sculpt, merge, or manually restructure the mesh, you need a tool with direct manipulation capabilities. Blender is the best free option for this.
Batch processing — if you need to repair hundreds of files, a scriptable tool (MeshLab with its scripting interface, or Python with trimesh) is more efficient.
Advanced repairs — severe self-intersections, complex surface reconstruction, or remeshing require specialized algorithms that go beyond topology repair.
Non-mesh tasks — support generation, slicing, build platform layout, and other print preparation tasks are outside the scope of mesh repair.

The 80/20 rule of STL repair: An estimated 80% of mesh issues are simple topology errors (non-manifold edges, flipped normals, small holes) that automatic repair handles perfectly. The remaining 20% may need manual intervention. JustFixSTL is designed to handle that 80% as quickly and easily as possible.

Slicer Built-In Repair: A Note

Many slicers (PrusaSlicer, Cura, OrcaSlicer) include built-in mesh repair. This is convenient, but there are reasons to prefer a dedicated repair step:

Transparency — slicer repair is a black box. You do not know what was changed. A dedicated repair tool shows you the before and after.
Reliability — slicer repair engines are tuned for speed and may not handle all defects. A dedicated tool uses more thorough algorithms.
Portability — if you repair the STL once, the clean version works in any slicer. If you rely on slicer repair, switching slicers may produce different results.
Confidence — knowing your mesh is clean before slicing lets you focus on print settings instead of wondering whether a print failure is a mesh issue or a settings issue.

Free STL Repair Tool — No Software Required