Convert binary STL to readable ASCII STL locally - for inspecting, versioning and diffing. No upload.
Running locally on your device ...
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Your files never left your device
No. Everything runs in your browser - your file never leaves your device. How this is verifiable
STL comes in two flavours: binary (compact, the usual case from CAD and 3D printing) and ASCII (plain text in which every triangle appears as readable lines). If you want to inspect a model, store it traceably in a version control system like Git, or compare two states (diff them), you need the text form. This tool reads your binary STL and writes the same model as ASCII STL.
The conversion is lossless for the geometry: every triangle and every coordinate is carried over unchanged, only the representation switches from bytes to text. The result begins with solid, lists a normal and three vertices per triangle, and ends with endsolid - exactly the structure a human can read and a text editor can compare line by line.
Everything runs entirely locally in the browser - your possibly confidential model never leaves your device. Honestly framed: ASCII STL is markedly larger than the binary form, but readable. For 3D printing itself the binary variant is usually a better fit (see STL ASCII to binary). A file that is not valid STL is rejected with a clear message.
| Input formats | STL |
|---|---|
| Output format | STL |
| Batch processing | No |
| Processing | Locally in your browser (JavaScript) |
| File upload | None |
Limitations: Converts binary STL to readable ASCII STL (lossless for the geometry): every triangle and coordinate is kept, only the representation switches to plain text. ASCII STL is markedly larger than the binary form. ASCII input is accepted too (passed through). A file that is not valid STL is rejected with a clear error.
For inspecting individual triangles, storing traceably in Git and comparing two model states line by line.
No. The conversion is lossless for the geometry; only the representation switches from bytes to text.
Yes, ASCII STL is markedly larger than binary STL. For storage and printing the binary form is more compact.
No, the conversion happens entirely locally in the browser; your model never leaves your device.