PDF page numbers

PDF readers know how many pages a document has, but they don't stamp the number onto the page itself. That matters whenever the document leaves the reader:

• Printed handouts and reports — readers need a number on every sheet to track where they are.
• Legal and academic submissions — most courts and journals require visible "Page n of N" on every page.
• Contracts and signed bundles — page numbers make tampering easier to spot (a removed page leaves a gap in the run).
• Books exported as PDF — InDesign, LaTeX and most writing apps add numbers automatically, but a one-off PDF export (e.g. a Word doc converted to PDF) often skips them.

Formats. Four templates cover the common conventions: just the number (1), prefixed with "Page" (Page 1), with the running total (1 of 12), or both (Page 1 of 12). The total N is the count of numbered pages — skipped pages don't inflate it.

Position. Six anchors cover every common layout: top-left, top-center, top-right, bottom-left, bottom-center and bottom-right. Bottom-center is the default; bottom-right is common for legal documents; top-right is the academic norm.

Starting number. If your "real" content starts on a later page — e.g. a 3-page foreword followed by Chapter 1 at the physical page 4 — set Skip first N to 3 and Starting number to 1. The first numbered page then reads "Page 1 of N".

• Pages with different sizes. The anchor uses each page's actual size, so numbers stay correctly inset on mixed-size PDFs (landscape + portrait, A4 + Letter).
• Rotated pages. pdf-lib draws relative to the underlying page geometry. If a page is rotated 90°, the number will follow the rotation in viewers that honour the rotate flag.
• Encrypted PDFs. Remove the password first (Save as → without password in your reader), then re-add numbering.
• Numbers overlap existing content. Raise the margin (default 36 pt = 0.5 in). The text sits inside that margin from the nearest edge.

The PDF is loaded into a Web Worker, pdf-lib appends one draw instruction per numbered page, and the modified PDF is offered as a download. There's no network round-trip and no server-side copy at any step.

Use this tool when you need a fast, one-off PDF task and want the document to stay in your browser. Desktop editors or command-line tools are better for heavily encrypted files, regulated review workflows, or very large batch jobs that need repeatable automation.

• Password-protected, digitally signed, or archival PDFs may need a specialist workflow before editing.
• Large scans can use a lot of memory, especially on phones or older laptops.
• Check the downloaded file before replacing the original, because compression, OCR, or conversion can change visual details.