Move the words
Document conversion here is about the words. A DOCX, a text file, HTML, or RTF can move to another text format in the browser. A designed brochure, with exact fonts and floating images, should be exported from Word, Google Docs, or the tool that created it.
XPS is the exception that does not convert in the browser. Windows can print XPS to PDF locally.
If you already know the job, start with Word to Excel or Excel to Word.
Every format on the site is listed from the homepage.
Designed pages belong in Word or Docs
Open the tool that names your two formats and read what the download will contain before you delete the original. If a result does not match that description, tell us.
Words travel. Layout usually does not
DOCX, TXT, HTML, RTF, and Markdown can exchange wording in the browser. A designed brochure should be exported from Word, Google Docs, or the tool that built it. Legacy DOC binary files cannot be read here. If you upload a real old .doc, the page stops and tells you to Save As DOCX on a computer that can open it. A file that is already DOCX can be re-saved. That is not the same as converting Word 97.
DOCX to DOC, for a portal that still names the old extension, extracts text into a Word file the browser can write. Images and text boxes are not rebuilt. HTML and XML become the words, not the live website and not a data schema. Markdown headings that start with a hash become simple headings. A Word file saved as Markdown is paragraphs, not a perfect map of bold and links.
XPS does not convert in the browser. Windows can print it to PDF. Keep the editable original. These downloads are for reading or a simple handoff.
If the document is a form with boxes in fixed places, a text conversion will scramble the boxes even when every word is present. Export PDF from the original app for that kind of page. Use these tools for notes, drafts, articles, and simple letters. A legacy DOC file needs Word or LibreOffice on a computer before any browser tool can see the words. After you have a DOCX, the browser tools can move the words to text, HTML, RTF, or Markdown. They still will not rebuild a letterhead. Keep the DOCX as the file you edit next week.
Letters, notes, and brochures are not the same job
A note or a draft can move between DOCX, text, HTML, and Markdown in the browser. A brochure with a letterhead and floating images should be exported from Word or Google Docs. The browser result will have the words and lose the design. That is useful for a quote you need to paste. It is a bad surprise in a client PDF.
Old DOC files need a desktop Save As before they become DOCX. XPS needs Windows Print to PDF. After you have a modern DOCX, keep it. Every text export is a copy for a specific reader, not a replacement for the file you will edit tomorrow.
Comments and tracked changes in Word may not appear in a text export, or they may appear as extra paragraphs. Turn comments off or accept changes in the desktop app if the export looks longer than the page you remember. The browser is showing the text it could read. It is not inventing sentences. If the word count jumped, look for comments that were included, then export again from a clean copy.