dkhylan·14 anni fa·discussGroupDocs provides a commercial online viewer and API's for supporting those formats as well as .pdf
dkhylan·14 anni fa·discussIf your looking for a web based API for manipulating PDF's, SaaSpose provide a commercially supported solution
dkhylan·14 anni fa·discussGroupDocs currently provide an app for online annotation and collaboration, including accessing your files from different cloud storage providers, currently Azure & Amazon S3 are supported http://groupdocs.com/apps/annotation/try-it-now