GeometryViewer vs ViewSTL — Full Comparison

ViewSTL has been around for years. It was one of the first web-based STL viewers, and it earned a loyal following by being simple, fast, and free. If you've ever Googled "view STL online," you've almost certainly landed on ViewSTL.com.

GeometryViewer is newer. It launched with a different set of priorities: broader format support, material visualization, AR, sharing, and embedding. But both tools serve the same fundamental purpose — letting you see a 3D model in your browser without installing anything.

So how do they actually compare? Here's an honest, feature-by-feature breakdown.

Feature comparison

Where ViewSTL wins

Being honest about the competition matters. Here's where ViewSTL genuinely has strengths:

Simplicity

ViewSTL is dead simple. The page loads, you drop a file, you see it. There are almost no UI elements, no panels, no menus to navigate. For someone who just wants to see what an STL file looks like with zero distraction, ViewSTL's minimalism is a feature, not a bug.

Established reputation

ViewSTL has been around for years and has strong search engine presence. Lots of 3D printing guides and forum posts link to ViewSTL as the go-to online viewer. This means your clients, colleagues, and students may already know it.

Embedding simplicity

ViewSTL provides a simple iframe embed code that you can paste into any website. It's been used on thousands of blog posts and project pages. The embed is lightweight and loads quickly.

Speed for basic viewing

For its core use case — opening a single STL file and spinning it around — ViewSTL loads fast and renders efficiently. There's no overhead from features you might not need.

Where GeometryViewer wins

Format support

This is the most significant difference. ViewSTL handles only STL files. GeometryViewer handles STL, OBJ, GLTF, GLB, and 3MF. If you work with anything other than STL — and most people do — this matters enormously. GLTF/GLB is the standard for web 3D. OBJ is common for 3D scans. 3MF is the modern 3D printing format. Having one viewer that handles all of them is more practical than bookmarking multiple single-format viewers.

Material visualization

ViewSTL shows models in a small selection of flat colors — white, red, blue, etc. It's a basic material with simple shading. GeometryViewer offers 24 material presets across six categories (Plastics, 3D Print, Metals, Aged, Wood, Special). These use PBR (Physically Based Rendering) with HDRI environment lighting for realistic reflections and surface detail.

For someone trying to show a client what a chrome-plated product looks like, or preview a wood-grain finish, or simulate 3D print layer lines, the material system makes a meaningful difference in communication quality.

Augmented reality

GeometryViewer supports AR on both iPhone (via Quick Look) and Android (via WebXR). Open a model, tap "View in AR," and the model appears at real-world scale in your room through your phone's camera. ViewSTL has no AR support.

AR is particularly valuable for 3D printing (checking print size before committing filament), product design (showing clients how a product fits in their space), and education (engaging students with interactive real-world models).

Sharing

GeometryViewer lets you generate a shareable link for any model. Click "Share," get a URL, send it to anyone. The recipient sees the interactive 3D view in their browser. ViewSTL doesn't have this feature — you'd need to send the actual STL file and have the recipient open ViewSTL separately.

Embedding

Both tools support embedding, but GeometryViewer's approach is more modern. In addition to basic iframe embedding, GeometryViewer provides a web component (two lines of code) and oEmbed support (paste a link in WordPress, Ghost, Notion, or any oEmbed-compatible platform and it auto-embeds). ViewSTL only offers basic iframe embedding.

3D print preview

GeometryViewer includes a 3D print preview feature that simulates layer lines at different layer heights. This gives you a visual approximation of what the print will look like at 0.1mm, 0.2mm, or 0.3mm layers — helpful for checking if fine details will survive the print. ViewSTL doesn't have print-specific features.

No ads

ViewSTL includes banner advertising on the page. GeometryViewer has no advertising. This matters for professional contexts where you're sharing a viewer link with a client — ads look unprofessional and can be distracting.

Use cases: which one to choose

Choose ViewSTL if you exclusively work with STL files, you want the simplest possible interface, and you don't need materials, AR, sharing, or embedding beyond basic iframes.

Choose GeometryViewer if you work with multiple 3D formats, you need to share models with clients or colleagues via link, you want material visualization or AR, or you need ad-free embedding for professional contexts.

Can you use both?

Absolutely. They're both free, both work in the browser, and both process files client-side. There's no lock-in, no account to manage, no switching cost. Use whichever one fits the task at hand.

That said, if you're going to bookmark one viewer for daily use, a tool that handles all common 3D formats (not just STL) is more practical in the long run. The 3D ecosystem is moving toward GLTF/GLB for web delivery and 3MF for 3D printing, and having a viewer that keeps up with that evolution saves you from hunting for format-specific tools.