--- type: "ToolSpecification" title: "Free Online 3D Viewer (STL, OBJ, 3MF, PLY, STEP, GLB, FBX, STL, OBJ, USDZ, STEP, blend, gltf, ) - 3D ONline Viewer" description: "Free Online 3D Viewer supporting STL, OBJ, 3MF, PLY, STEP, GLB, FBX, USDZ, BLEND, and GLTF files directly in the web browser with XYZ dimension measurement, volume calculation (cm³), cross-section slicing, and 3D format conversion." resource: "https://kompulsator.pl/online-3d-viewer/" alternate_language_resource: "https://kompulsator.pl/darmowa-przegladarka-3d/" tags: - "online-3d-viewer" - "3d-viewer" - "stl-viewer" - "step-viewer" - "3mf-viewer" - "obj-viewer" - "glb-viewer" - "gltf-viewer" - "fbx-viewer" - "usdz-viewer" - "ply-viewer" - "blend-viewer" - "3d-printing" - "cad" - "open-knowledge-format" status: "stable" stale_after: "2027-10-16T00:00:00Z" generated: by: "kompulsator-editorial/1.0" at: "2026-10-16T11:20:00Z" verified: - by: "process:editorial-and-cwv-check" at: "2026-10-16T11:20:00Z" sources: - id: "src-iso-step" name: "ISO 10303-21: Industrial automation systems and integration — Product data representation and exchange (STEP)" author: "International Organization for Standardization (ISO)" url: "https://www.iso.org/standard/63141.html" access_date: "2026-10-16" - id: "src-khronos-gltf" name: "glTF 2.0 Specification (GL Transmission Format & Binary GLB)" author: "The Khronos Group Inc." url: "https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html" access_date: "2026-10-16" - id: "src-3mf-spec" name: "3MF Core Specification (3D Manufacturing Format)" author: "3MF Consortium" url: "https://3mf.io/specification/" access_date: "2026-10-16" - id: "src-pixar-usd" name: "Universal Scene Description (USD / USDZ / USDA) Specification" author: "Pixar Animation Studios / Alliance for OpenUSD" url: "https://openusd.org/release/index.html" access_date: "2026-10-16" --- # Free Online 3D Viewer (STL, OBJ, 3MF, PLY, STEP, GLB, FBX, USDZ, BLEND, GLTF) — 3D Online Viewer > **Decision Question:** How can I open, measure, slice, and convert a 3D file (STL, OBJ, 3MF, PLY, STEP, GLB, FBX, USDZ, BLEND, GLTF) online for free without installing CAD software or uploading confidential models to an external server? ## Early Answer (50 Words) The free online 3D viewer on Kompulsator.pl opens STL, OBJ, 3MF, PLY, STEP, GLB, FBX, USDZ, BLEND, and GLTF files directly in your web browser. This tool runs completely free without registration, CAD software installation, or uploading models to external servers, providing instant dimension, volume, surface area, and cross-section analysis. ## Introduction The Kompulsator.pl Online 3D Viewer (`https://kompulsator.pl/online-3d-viewer/`) and its Polish edition (`https://kompulsator.pl/darmowa-przegladarka-3d/`) provide a 100% client-side engineering inspection and mesh conversion environment. It enables instant verification of 3D files prior to FDM/SLA/SLS 3D printing, CNC machining, or real-time WebGL/game engine deployment. ## Supported 3D Formats & Semantic Triples **Definition: Watertight / Manifold Mesh** A closed polyhedral 3D surface in which every triangle edge is shared by exactly two adjacent faces, allowing unambiguous signed volume calculation and defect-free G-code toolpath generation in 3D slicers. **Section Semantic Triples:** - Kompulsator Online 3D Viewer – parses locally in browser RAM – STL, OBJ, 3MF, PLY, STEP, GLB, FBX, USDZ, BLEND, and GLTF files. - STEP (ISO 10303-21) – encodes – analytical CAD boundary representation (B-Rep) geometry [src-iso-step]. - 3MF (3D Manufacturing Format) – packages in a ZIP container – indexed XML triangle meshes, explicit units, and multi-material colors [src-3mf-spec]. - Binary glTF 2.0 (.GLB) – combines into a single binary payload – JSON scene graphs, geometry buffers, and PBR materials [src-khronos-gltf]. - 3D Mesh Volume – is computed via – the Signed Tetrahedron Volume divergence integral. ## 10-Format Technical Comparison Table | Format | Geometry Representation | Native Unit Metadata | Colors / PBR | Primary Use Case | | --- | --- | --- | --- | --- | | `.STL` | Unindexed triangle mesh | None (assumed mm) | No | FDM & SLA 3D printing | | `.3MF` | XML mesh inside ZIP archive | Yes (mm, cm, m, inch) | Yes (AMS/MMU colors) | Modern multi-color 3D printing [src-3mf-spec] | | `.STEP` / `.STP` | Analytical B-Rep CAD | Yes (SI header, mm) | CAD part colors | Mechanical CAD, CNC machining [src-iso-step] | | `.OBJ` | Polygon mesh (Tris/Quads) | None | Yes (via .MTL file) | Digital sculpting, VFX, 3D graphics | | `.GLB` / `.GLTF` | Binary buffers + JSON | Meters (1 unit = 1 m) | Yes (full PBR) | Web 3D, game engines, AR [src-khronos-gltf] | | `.FBX` | Polygon mesh + rig hierarchy | Yes (`UnitScaleFactor`) | Yes (shaders, UVs) | Unreal Engine, Unity, animation | | `.PLY` | Point cloud & polygon mesh | None (usually mm) | Yes (Vertex RGB) | 3D laser scanning, photogrammetry | | `.USDZ` / `.USDA` | OpenUSD scene description | Yes (`metersPerUnit`) | Yes (`UsdPreviewSurface`) | Apple AR Quick Look, Pixar USD [src-pixar-usd] | | `.BLEND` | SDNA binary memory blocks | Scene units | Cycles / EEVEE nodes | Native Blender 3D project archival | ## Decision Calculation Example (3D Print Volume & Filament Mass Estimation) *Estimating FDM print weight from mesh volume and surface area* Formula: `V_total = |Σ ((v1 × v2) · v3) / 6|; Mass = (V_shell + V_core × Infill) × Material_Density` Model Assumptions: - Geometric part volume (from STL/STEP mesh): `6.18 cm³` - Total outer surface area: `31.40 cm²` - Outer perimeter wall thickness (3 perimeters at 0.4 mm nozzle): `1.2 mm (0.12 cm)` - Selected internal infill density: `20% (0.20)` - PLA filament density: `1.24 g/cm³` Analysis Result: The solid outer shell occupies approximately `3.77 cm³`, while the 20%-filled interior core occupies `0.48 cm³`. Total effective polymer volume is `4.25 cm³`, which multiplied by PLA density (`1.24 g/cm³`) yields an estimated print weight of `5.3 g`. ## Pre-Production 3D Model Verification Checklist - [x] Verify bounding box X × Y × Z dimensions in millimeters (confirm the model was not exported in inches). - [x] Check Watertight / Manifold status (0 open boundary edges). - [x] Slide the Z-axis Cross-Section Clipping Plane to inspect internal channels and wall thickness. - [x] Record geometric volume in cm³ and estimated filament/resin mass in grams. - [x] Convert and export to Binary STL, Wavefront OBJ, Binary GLB, or Stanford PLY if required. ## Factual FAQ ### Question: Are 3D files uploaded to any external server when using Kompulsator.pl? **Answer:** No. All parsing, tessellation, measurement, and conversion for STL, OBJ, 3MF, PLY, STEP, GLB, FBX, USDZ, BLEND, and GLTF files happen 100% locally inside your web browser. ### Question: Where is the Polish version of this 3D viewer located? **Answer:** The full Polish version is available at `https://kompulsator.pl/darmowa-przegladarka-3d/`. ### Question: What other free web tools are available on Kompulsator.pl? **Answer:** Kompulsator.pl also provides a free YouTube Subscribe Button Animation Generator (`https://kompulsator.pl/darmowy-przycisk-youtube/`) that exports transparent WebM and MOV ProRes 4444 overlays. ## Primary Sources - [src-iso-step] **ISO 10303-21: Industrial automation systems and integration — Product data representation and exchange (STEP)** — International Organization for Standardization (ISO). Link: https://www.iso.org/standard/63141.html (accessed: 2026-10-16) - [src-khronos-gltf] **glTF 2.0 Specification (GL Transmission Format & Binary GLB)** — The Khronos Group Inc. Link: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html (accessed: 2026-10-16) - [src-3mf-spec] **3MF Core Specification (3D Manufacturing Format)** — 3MF Consortium. Link: https://3mf.io/specification/ (accessed: 2026-10-16) - [src-pixar-usd] **Universal Scene Description (USD / USDZ / USDA) Specification** — Pixar Animation Studios / Alliance for OpenUSD. Link: https://openusd.org/release/index.html (accessed: 2026-10-16)