OneRender is described as 'empowers you to create Photorealistic Renders in the Cloud, without the cost of a license. All you need is a web browser, there is nothing to download or to install'. There are four alternatives to OneRender, not only websites but also apps for Windows, Mac and Linux. The best alternative is Keyshot. Other great sites and apps similar to OneRender are Maxwell (Paid), Maverick Studio (Paid) and PhotoView 360 (Paid).
Maverick Studio is a GPU-accelerated render engine for engineers, designers and artists. Capable of outstanding quality and performance, it packs an impressive list of features at an aggressive price point. Anyone can try it for free, for 30 days.
PhotoView 360 is the new visualization and rendering solution from Solidworks. Its a highly interactive environment for viewing your designs as well as for creating photorealistic renderings that you can use to showcase your designs.