Document conversion
Definition
Transforming a file from one format into another and producing a new file, as distinct from rendering, which produces a temporary visual representation and no new artifact.
The two are easy to confuse because both start by interpreting the source document. The difference is what remains afterwards. Rendering leaves you with page images the viewer serves and eventually evicts. Conversion leaves you with a file that has its own lifecycle, its own storage cost and its own retention question.
That difference decides which one you want. If the requirement is "users need to read this", rendering is the cheaper answer — one copy of the document, nothing to re-run when it changes. If the requirement is "we must archive an immutable PDF of what was agreed on the 4th", conversion is the only one that satisfies it.
Conversion between structured formats is inherently lossy in ways rendering is not. PDF to DOCX in particular is a reconstruction, because a PDF records where glyphs sit on a page and not what a paragraph is.
In Doconut
Conversion is a separate paid plugin, invoked with DocumentConverter.ConvertAsync(...). It runs in the same process as the viewer, so there is no second service and no temporary upload anywhere.
Related terms
Server-side document rendering
Converting a document into page images on the server, so the browser displays rendered pages rather than parsing the original file itself.
Text layer
The machine-readable text stored inside a document alongside its visual appearance. It is what makes search and text selection possible, and it is exactly what a scanned page does not have.
Office interop (server-side automation)
Driving Microsoft Office from code to open or convert documents. It works on a desktop and is explicitly discouraged on a server, by Microsoft as well as by everyone who has tried it.