obj-to-html is a small application that converts a 3D model in .obj format into HTML and CSS that will display that model in a web browser, spinning around its Y axis. This is achieved through creative abuse of CSS's 3D transforms. It supports triangle-based models and can pick up diffuse colours and textures from a .mtl file. I've tested it on a handful of models from Models Resource.
This is absolutely not the best way to display a 3D model in the browser — please use WebGL for serious projects! But it is quite fun to use on websites like cohost that let you make posts containing arbitrary inline CSS, but not inline JS. For example, this post where I show off Lara Croft from Tomb Raider (and announce this project!)
This was written by me over three days (24th to 26th November 2022). Special thanks to cassie who listened to my rambling about the project and made some helpful suggestions. ^^
In January 2023 I wrote a blog post about the project, if you want to know a bit about the process.