How to add page numbers to a PDF
- Drop your PDF into the zone above, or click to browse and select it.
- Choose a position — bottom center is standard for most documents; bottom right suits formal reports.
- Set the starting number. Use 1 for a standalone document, or a higher number if this PDF continues a larger work.
- Click Add numbers & download. The numbered PDF saves directly to your device.
Everything runs in your browser using pdf-lib.
No file is uploaded — open DevTools (F12) → Network while processing to confirm zero outbound requests.
When to add page numbers to a PDF
- Preparing a document for printing — readers can navigate and reassemble printed pages easily with numbered footers.
- Formal reports and submissions — legal filings, academic submissions, and business proposals are expected to have page numbers.
- Multi-chapter documents — number each chapter PDF starting from where the previous one ended to create consistent pagination across a series.
- Scanned documents — add numbers to a scanned PDF that was produced without them.
- Contract annexures — stamp page numbers before sending contracts for signature to prevent page substitution.
How it works under the hood
pdf-lib loads your PDF and provides access to each page's content stream. For every page, the tool
calculates the position of the page number text based on the page's actual dimensions (which may vary
if the PDF has mixed page sizes), then calls page.drawText() to add a Helvetica text
element at the correct coordinates.
Helvetica is one of the 14 standard PDF fonts — it is available in every PDF viewer without needing to be embedded in the file, which keeps the output file size nearly identical to the input. The text is drawn as a proper PDF text object, so it is selectable and searchable in the output document.
Limits and what to expect
- Font and size: Helvetica at 11pt. These are fixed to keep the tool simple and the output consistent — custom fonts and sizes are not currently available.
- Margin overlap: numbers are placed at a fixed margin from the page edge. If your PDF has content running to the very edge (no margin), numbers may overlap the content — check the output before sharing.
- Mixed page sizes: the tool handles PDFs with different page dimensions correctly, placing numbers at the same relative position on each page regardless of size.
- Existing page numbers: if the PDF already has printed page numbers, this tool adds a second set on top of them. Remove the old numbers first using a PDF editor.
- Password-protected PDFs: must be unlocked before use. The tool will fail on PDFs that restrict content editing.
Privacy compared to other page numbering tools
Most online PDF tools upload your document to their server to process it. For reports containing financial projections, legal filings, or client data, that upload is a potential data leak — regardless of what the tool's privacy policy says about deletion windows.
keptlocal stamps page numbers entirely inside your browser. Your PDF bytes never leave your device. Open the Network tab in DevTools and run the tool — you will see no upload requests at all.