Yes. PlanetForge is 100% free with no signup. Models, textures and projects are processed entirely in your browser and never uploaded.

What 3D formats can I import?

Wavefront OBJ files. Polygon faces are triangulated on import and the mesh is normalized so it always frames correctly in the viewport.

How does the smart unwrap work?

Adjacent faces are grouped into islands wherever the angle between them is below your seam-angle threshold, each island is projected on its dominant plane keeping real-world proportions, and the islands are packed into the 0-1 UV square with your chosen pixel padding.

Can I paint like in Substance Painter?

PlanetForge gives you a layered 1024x1024 base-color canvas with brush, eraser, island fill and color picker, plus size, opacity and hardness controls. Strokes commit with uniform opacity like a real painting app, and Ctrl+Z undoes them.

Yes. Save the whole project - mesh, UV islands, layers and material settings - as one JSON file and load it back later. The composited texture also exports as PNG.

PlanetForge - Free Online UV Unwrap & 3D Texture Painting Tool (OBJ)

Import an OBJ model, generate clean packed UV islands with angle-aware smart unwrapping, paint the texture in layers with brush, fill and eraser, and preview roughness, metallic and bump on a material sphere - free, no signup, nothing ever uploaded.

What is PlanetForge?

PlanetForge is a small, private 3D surfacing studio in the browser. It covers the three steps between a raw model and a textured one: UV unwrapping (cutting the surface into flat islands), texture painting (coloring those islands in layers), and material preview (checking how roughness, metallic and bump read under light). Everything - parsing, unwrapping, painting, rendering - runs locally; your models never leave your device.

How to texture a model

Import an OBJ (or start with the demo cube). The mesh appears in the 3D view - drag to orbit, scroll to zoom.
Unwrap it. Pick a seam angle - lower angles cut more seams and give flatter islands - and hit Smart unwrap & pack. Islands keep their relative real-world size, so texel density stays even across the mesh.
Arrange the islands. Click one in the UV view to select it, drag to move, or rotate and flip it with the island tools.
Paint. Switch to the Paint workspace and color the layout with brush, island fill and eraser across as many layers as you like. The 3D view shows your paint mapped back onto the model.
Check the material. The Material workspace wraps your texture around a sphere with roughness, metallic, bump and a movable light in three environments.
Export the composited texture as PNG, or save the whole project as JSON to continue later.

Tips

Seam angle ≈ 58° works for most hard-surface models; drop it toward 30° for organic shapes that need flatter islands.
Island fill first, details after: block in each island's base color with the fill tool, then paint highlights on a second layer so you can erase without losing the base.
Generate source textures in PlanetTex - export any procedural texture there as PNG and import it straight into a paint layer here.
Padding prevents bleeding: if colors from one island leak into a neighbor on the model, repack with more island padding.

FAQ

Is my model uploaded anywhere?

No. PlanetForge is a static page - OBJ parsing, unwrapping, painting and rendering all happen in your browser. There is no server to upload to.

What resolution is the texture?

The paint canvas is 1024 × 1024. The exported PNG matches it exactly, with transparency where nothing was painted.

Which unwrap method should I use?

Smart (angle based) follows the surface and is right for almost everything. Box projection groups faces by the axis they point along - useful for boxy, architectural meshes where you want exactly six-sided-projection style islands.

Can I use the textures commercially?

Yes. Everything you paint and export is yours, for personal or commercial projects, no attribution required.