Hi Yudho,
Thank you for your interest in Syncfusion products.
It is possible to open a document, edit it and save it locally in the computer. Opening an existing document and saving it to the computer locally is achieved by using the following code snippet.
[C#]
IWordDocument document = new WordDocument(Server.MapPath("Sample_Doc.doc"));
Here is the sample program for your reference.
http://websamples.syncfusion.com/samples/DocIO.Windows/F-65117/main.htmRegarding saving back to the server can you explain the issue in detail which will be more helpful for us to investigate further in this issue.
Please let me know for further help.
Regards,
Sarath