.NET API for document viewing and editing.

Question

We are building a document management system in ASP.NET. This application should support document (office documents, PDF and TIFF) viewing and editing on line (in the browser itself). We are looking for a third party component which offers these services. The API/SDK should not use any ActiveX or InterOp services.

The documents are stored on the client file repository (we can't use Google Drive as the documents must be stored on Google drive). The API/SDK should not store documents on their server. It must be able to use our own file repository and perform actions on the document.

Currently we are exploring ZOHO Remote API. However, ZOHO doesn't support TIFF editing and PDF viewing. It only supports office documents viewing and editing.

We are looking for an imaging SDK for .NET that can provide the features below

- Document (office documents like word, presentation, excel, PDF, TIFF) Viewing and Editing.
- Annotations and Redacting features
- Zoom feature
- Generate thumbnail of the documents

We have been googling for so long to find the right component. We have explored so many SDKs in this process. Could anybody suggest us right SDK which can do the above?

Your help is very much appreciated.

Thanks,
Srikar