About STL Repair
A free browser-based tool for one job: making a broken STL printable again — and telling you what was actually wrong with it.
Why this site exists
There is no shortage of online STL repair tools. Almost all of them work the same way: you drag a file in, watch a spinner, and download something. You are not told what was wrong, what was changed, or whether it actually worked. If the repair silently failed, you find out an hour into a print.
That black box is the reason this site exists. The repair engine already knows exactly what it did — how many holes it sealed, how many faces it turned the right way round, how many degenerate triangles it stripped out. Most tools throw that information away. This one shows it to you in plain language.
How it works
The repair engine is compiled to WebAssembly and runs inside your browser, on your own machine. Your model is never uploaded, never stored, and never leaves your computer. You can load this page, disconnect from the internet, and it still repairs files.
The geometry work is done by open-source libraries — the same boolean and mesh-healing code used in production by tools like Blender, Godot and OpenSCAD. This site is the interface and the diagnostics around them, not a from-scratch geometry engine, and it would be dishonest to imply otherwise.
What it will not do
A repair tool cannot invent geometry that was never in the file. Holes are closed with flat patches, so a large missing region comes back bridged rather than reconstructed. Very large models hit the memory ceiling of a browser tab — the tool reads your file's triangle count first and tells you upfront when a desktop application is the better choice, instead of letting you wait and fail.
Some checks are skipped on large meshes because they would take longer than the repair itself. When that happens the report says the check was not run. It never reports "clean" for something it did not look at.
Who runs it
STL Repair is built and maintained by an independent developer. There is no company behind it, no team, and no investors. The site is free, requires no account, has no usage limit and no paid tier, and is supported by advertising.
Not affiliated with any of the tools mentioned
Pages on this site compare it with Meshmixer, Netfabb and MeshLab so you can decide which fits your job. This site is independent and is not affiliated with, endorsed by, or sponsored by Autodesk, ISTI-CNR, or any other software vendor. Statements about other tools were checked at the time of writing and are dated on the page where they appear.
Found a model it handled badly? That is worth hearing about — a file that comes back worse than it went in is a bug, and the repair log makes it possible to work out why.
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