Shipping a “free converter” is easy to oversell. Geometry tools in the browser have sharp edges: units, textures that are not geometry, triangle budgets, and users who treat a preview as a print certificate.
This note is what we chose to expose—and refuse—when we added two free tools next to Text to STL’s generator:
Local processing as a product constraint
Both tools process files in the browser. Nothing is uploaded for conversion or viewing. That choice is privacy-friendly and also a performance ceiling: a phone tab is not Meshy’s backend.
Practical caps we ship today:
- 50 MB max file size
- 100,000 triangles max
- Static, self-contained GLB only for conversion (no external resources, animation, or skinning)
Crossing those lines fails loudly in the UI instead of hanging the tab.
STL is not a pretty GLB
Standard STL stores a triangle surface. It does not keep materials, textures, or animation. Surface detail that exists only as a texture will not become physical geometry after conversion. The converter FAQ states that explicitly; the UI compares original GLB vs STL so the loss is visible before download.
Units: metres meet “no unit”
GLB coordinates commonly use metres. STL has no unit field. We do not auto-convert metres to millimetres. Silent scaling would look convenient and then print ten or a thousand times too small. The copy tells people to confirm size in the slicer—annoying, correct.
Viewer ≠ printable
The STL viewer shows shape, approximate axis-aligned dimensions in model units, and triangle count. It does not repair meshes, measure wall thickness, or certify printability. That boundary is boring product writing and the difference between a helpful free tool and a support queue.
Why put free tools beside a paid generator
The generator path is text/image → mesh with credits. The free tools catch a different job: someone already has a GLB or STL and needs a private convert or a first look. Cross-links between converter, viewer, and generator keep the funnel honest—use the free path when you do not need AI generation.
Disclosure
I built Text to STL. This article describes shipped behaviour on the live tool pages as of publishing; it is not a benchmark against every online converter. Drafted with autonomous AI assistance; I reviewed the technical claims against the product FAQ and live pages.
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