Will the OBJ have colors or materials?

No — STL never contained material or color information to begin with, so there's nothing to carry over. The resulting OBJ is pure geometry, same as the source STL, just in a format more editing software can open directly.

Why convert STL to OBJ instead of just opening the STL directly?

Many 3D editing and modeling tools support STL only partially or not at all, while OBJ has near-universal support across modeling software. Converting first avoids compatibility issues when you want to edit, remesh, or inspect a model's structure.

Does this work with both ASCII and binary STL files?

Yes, three.js’s STLLoader automatically detects and handles both STL variants, so either format converts the same way.

Will the converted OBJ be editable in Blender?

Yes, Blender (and most other 3D software) opens standard OBJ files natively, and the geometry will appear exactly as it was in the source STL, ready for editing.

Is there a polygon count limit?

No hard limit is built into the tool. Very high-poly STL models will take longer to parse and export and use more browser memory, but there's no server-imposed restriction.

Is my STL file uploaded anywhere during conversion?

No. three.js parses and re-exports the geometry entirely in your browser — your model file never leaves your device.

Will the OBJ include a separate .mtl material file?

No, since the source STL has no material data, there’s nothing to generate a .mtl file from — the OBJ output references no external material file.

Does this repair broken or non-manifold geometry?

No, the conversion preserves your source geometry exactly as described in the STL, including any gaps or non-manifold issues the original file had. This tool doesn't perform mesh repair.

Can I convert a multi-part STL (multiple separate solids)?

Yes, all triangles in the STL are converted into one combined mesh in the output OBJ — STL doesn’t separately name multiple parts, so neither does the resulting OBJ.

Does this modify my original STL file?

No. The tool only reads the source file to generate a new, separate OBJ — your original .stl file is left completely untouched.

STL to OBJ Converter — Free Online, No Upload

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What is STL to OBJ?

STL files are deliberately minimal — just a flat list of triangles with no grouping, materials, or metadata — which makes them awkward to work with in general-purpose 3D modeling and editing software that expects a richer format. OBJ is the more broadly compatible interchange format most 3D editors (Blender, SketchUp, MeshLab, and dozens of others) handle natively, with support for named objects, materials, and texture coordinates even when those features aren't being used. This tool reads an STL's triangle mesh and re-exports it as a standard OBJ.

The conversion runs through three.js: STLLoader parses the binary or ASCII triangle data into a BufferGeometry, which is wrapped in a Mesh and handed to OBJExporter to produce OBJ-format text — a list of vertex positions (v), vertex normals (vn), and triangular faces (f) referencing those vertices. The geometry itself is preserved exactly; OBJ simply gives that same shape a format more editing tools are built to open directly.

Since STL never contained materials, colors, or textures to begin with, the resulting OBJ is geometry-only too — this conversion doesn't add information that wasn't there, it just repackages the same triangle mesh into a format with broader editing-software support.

Need to go the other direction and prepare a model for 3D printing? Use OBJ to STL.

How It Works

Your STL file's binary or ASCII triangle data is parsed by three.js's STLLoader into a BufferGeometry object, reconstructing every vertex position and face from the file. That geometry is wrapped in a Mesh object and passed to OBJExporter, which writes out the standard OBJ text format — vertex lines (v), vertex normal lines (vn), and face lines (f) that reference those vertices by index.

How to Use

Upload your STL file

Drop a .stl file (ASCII or binary) onto the upload area, or click to browse for it.

Click Convert to OBJ

three.js parses the triangle mesh and re-exports it as standard OBJ text.

Download the OBJ file

Save the result — it keeps your original filename with a .obj extension.

Open in your editor

Import the OBJ directly into Blender, SketchUp, MeshLab, or any other 3D editing software.

Who Uses This Tool

✏️

3D Model Editing

Open a downloaded STL in Blender or another editor to modify, remesh, or inspect it.

🔍

Model Inspection

Examine an STL’s underlying geometry structure in software with better analysis tools.

🎨

Adding Materials

Convert to OBJ as a first step toward adding colors, materials, or textures in an editor.

🔄

Pipeline Compatibility

Feed an STL into tools or game engines that expect OBJ rather than STL input.

📐

Reverse Engineering

Convert a 3D-scanned or downloaded STL into an editable format for further CAD work.

🧰

Mesh Repair Prep

Bring a problematic STL into mesh-repair-capable software that works better with OBJ input.

Why Choose This Tool

Standard three.js Pipeline

Uses the same parsing and export logic powering countless production 3D web tools.

Broad Editor Compatibility

OBJ output opens natively in nearly every 3D modeling and editing application.

Fully Local Processing

Parsing and export both happen in your browser — nothing is uploaded.

Exact Geometry Preservation

Vertex positions and triangulation are preserved precisely from source to output.

No Server-Side Size Cap

Local processing means no artificial ceiling on model complexity beyond your account plan.

Free, No Watermark

Free with no account for files under 40MB; sign up free for 80MB or go Pro for 250MB.

Key Benefits

Uses three.js, the standard JavaScript 3D library

Output opens natively in Blender, SketchUp, MeshLab, and more

Browser-based — your model is never uploaded to a server

Works with both ASCII and binary STL input

Preserves exact geometry and triangulation

No file size limit beyond your browser's available memory

No account needed for standard file sizes

100% free with no watermark

Frequently Asked Questions

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STL to OBJ