Pan0.net

I like pan0.net most of all. It is free, fast, and makes the panoramas look impressive. It uses a Flash-based spherical panorama viewer, which you can even embed into your own site or blog.

Unlike Gigapan, Panoramio and similar sites, pan0.net takes care of perspective transforms, and allows to view the panorama as if you were rotating the head in a first person shooter, it is not just zooming and panning a large flat image. It is much more immersive.

Features

• very immersive spherical panorama player (open source)
• support for 360°×180° and partial panoramas (if angle of view is set)
• interactive map reference (also the view direction on the map)
• hotspots on the panorama (text or image)
• virtual tours
• panoramas are embeddable (just like you embed youtube videos)
• small and large resolution views, view on black or view on white

Upload limits

• source panorama image can go up to 8000×4000, but it is effectively ‘rescaled to 5000×2500 for smooth panorama preview’;

Self-hosted panorama viewer

If you can afford to pay for hosting, you may choose to host images and a Flash-based or Java-based panorama viewer yourself. There are many choices. Some spherical panorama viewers I am aware of are:

• pan0 (open source, the same viewer which is used on pan0.net; Flash)
• krPano (90€, Flash, comes with tools for Windows, Mac and Linux; there is an option to order also a panorama viewer for iPhone)
• Pano2VR (from 71€ to 180€, Flash, comes with tools for Windows, Mac and Linux)
• ptviewer (open source, Java, an example of site using it)

Things not to use

Microsoft Photosynth uses Silverlight, and works only on Windows desktops; not very good for web, because cannot be viewed on Linux and many mobile devices. Installation of Silverlight on Mac is not always working as expected (according to forums).

Quicktime VR, it is not supported in the newer versions of Quicktime anymore (see Last nail in the coffin). It is a dead proprietary format.