That would require uploading all the input photos. Thats sometimes 50+ 20 MP images, none of which you are going to want to look at after you get the stitch done.

Id like to see a portable version that doesnt require install, but not an online version.

As much as I like services I love real honest apt-get-able open source ;-)

(Edit to add: Some of the hats some of us wore or wear comes with data that should n o t be uploaded to any cloud.)

I believe you mean "photostitching as a service"

If you have photo backup enabled to google plus, it will stitch your photos together sometimes.