Every week, millions of résumés, contracts, and reports get pasted into "free online converters" that quietly upload the whole file to somebody's server. It usually works out fine. When it doesn't — an NDA'd contract, a personnel review, a medical letter — there's no undo. Here's how the conversion actually works, what each method preserves, and how to get a PDF without your document ever leaving the machine.
Our Word to PDF converter is the third kind. It chains two open-source libraries — mammoth.js reads the .docx into structured HTML, then html-to-pdfmake and pdfmake typeset that into PDF bytes. Every step runs on your device.
A .docx file is a ZIP archive of XML, and it contains content, not pages. Pagination is computed when a program with the right fonts lays it out. That's why "pixel-perfect" is a promise no converter can honestly make without running Word itself. What a semantic conversion preserves:
| Element | Carries over? | Notes |
|---|---|---|
| Text, bold, italic | Yes | Re-typeset in the PDF's own fonts |
| Headings | Yes | Become real PDF headings with proper sizes |
| Lists (bulleted, numbered) | Yes | Rebuilt as PDF lists |
| Tables | Yes | Data and structure, not cell-level shading tricks |
| Hyperlinks | Yes | Stay clickable in the PDF |
| Inline images | Yes | Embedded at their original resolution |
| Exact fonts & layout | No | Requires the print engine that made them |
| Multi-column, text boxes | No | Flows into a single column |
| Headers, footers, page numbers | No | Add them after, in a PDF editor, if needed |
For letters, reports, manuscripts, and most business documents, that list covers everything that matters. For a designed brochure, use Word's own export.
PDFs measure in points: 1 point = 1/72 inch, exactly. The standard sizes are fixed numbers, not approximations:
Points also connect to what you see on screen: browsers draw at 96 pixels per inch, so one CSS pixel is 0.75 pt, and a Letter page is 816 × 1056 px in browser units. If you set 1-inch (72 pt) margins on Letter, the text column is 612 − 144 = 468 pt wide. At 12 pt type you'll fit roughly 500 words per page single-spaced — a 2,000-word report lands at about 4 pages before images and tables nudge it up.
The privacy argument is obvious, but there's a second one: durability. Upload converters rate-limit, queue at peak times, watermark free tiers, and shut down when the ads stop paying. A browser-side converter has no per-document cost, so there's nothing to ration — convert a hundred files and nothing throttles, because no server did any work.
You can audit the claim, too. Open your browser's developer tools, switch to the network tab, and run a conversion. You'll see library files load once from a CDN, then nothing — no request ever contains your document. An upload-based tool, run the same way, shows a large POST leaving the page. Ten seconds of checking beats any privacy policy paragraph.
Drop in a .docx, choose Letter, A4, or Legal, and download the PDF — the whole conversion happens in your browser. No signup, no upload, no watermark.
Open Word to PDF →Converting is usually step one of three. Step two is often signing the PDF — draw or type a signature, drag it into place, download. If you're starting from structured text instead of Word, the HTML to PDF converter typesets articles, invoices, and tables straight from markup, and CSV to Excel handles the spreadsheet side of the same document shuffle.
Use Word's export when you have Word and need its exact layout. Use a local browser converter when you don't have Word, or when the document shouldn't leave your machine — which, honestly, is most documents. Keep the .docx as your source of truth and treat the PDF as the frozen, shareable output.
If you have Word, use File → Save As → PDF — it's built in and free. If you don't, Google Docs and LibreOffice both export PDF for free after importing the .docx, and browser-based converters like ToolAspect's convert the file locally without an account. The differences show up in formatting fidelity and privacy, not in price.
It depends on where the conversion happens. Upload-based converters send your whole document to a server you don't control, and free ones often monetize with ads or retain files for hours. Browser-based converters do the work on your own device with JavaScript, so the document never leaves your machine — verifiable in the network panel. For contracts, résumés with personal data, or anything under NDA, local conversion is the sensible default.
Word documents don't have fixed pages — pagination is computed at print time from the fonts on the machine printing. Any converter that isn't running Word with your exact fonts has to re-typeset, so line breaks and page counts shift. Semantic content (text, headings, tables, images) survives; pixel-identical layout is only guaranteed by Word's own export on the same machine.
Only .docx. The .doc format from Word 97-2003 is a proprietary binary format, while .docx is a ZIP archive of XML — that openness is what lets free converters exist at all. To modernize an old .doc, open it in Word, LibreOffice, or Google Docs and re-save as .docx.