PDF Watermark — Add Text Watermarks in Your Browser

Image

PDF Watermark is a browser-based PDF tool that stamps the text you enter, with chosen opacity, size, and direction, across the center of every page and saves a new PDF.

PDF Watermark

Local processingFiles never leave your browser

Runs in your browser

Selected files and input are not uploaded to a server. Preview, conversion, hashing, and download file creation run in this browser session.

Supported input: 1 PDF file + text
Output: Watermarked PDF
Max file size: 50.00 MB
Encrypted PDF: Not supported

Drag a PDF file or click to choose

Watermark text

Opacity (0.05-1)

Size

Direction

What is it

Use a PDF watermark to mark document status or distribution scope with labels such as "CONFIDENTIAL", "COPY", or "DRAFT". The text is rendered into a high-resolution image using browser fonts and placed at the center of each page, so both Latin and non-Latin scripts (including Korean) are supported. You can combine opacity (default 0.15), size (small/medium/large), and direction (diagonal 45° or horizontal). The watermark is drawn on top of existing content and the source file is never modified. Files up to 50MB are supported and encrypted PDFs are not.

watermark = textImage × opacity(0.05–1) × rotation(0° or 45°)

How to use

1Choose the PDF file.
2Enter the watermark text, e.g. CONFIDENTIAL.
3Set opacity, size, and direction (diagonal or horizontal).
4Press the add watermark button and download the result.

Reference

PDF Watermark — Add Text Watermarks in Your Browser Reference
Option	Default	Range
Opacity	0.15	0.05 – 1
Direction	Diagonal 45°	Diagonal / horizontal
Size	Medium	About 40–70% of page width
Coverage	All pages	Once per page, centered

Sources & standards

ISO 32000-2 — Portable Document Format (PDF 2.0) - PDF Association
pdf-lib — Create and modify PDF documents in JavaScript - pdf-lib
MDN Web Docs: Client-side web APIs - MDN Web Docs

FAQ

Is my PDF uploaded to a server?

No. File selection, watermarking, and download creation all run in your browser; the file never leaves your device.

Are non-Latin watermarks like Korean supported?

Yes. The text is rendered to an image with browser fonts before insertion, so Korean and other Unicode scripts work as-is.

Is a watermark tamper-proof?

No. A watermark is a visual overlay and can be removed with editing tools. Use digital signatures for legally binding protection.

Can I watermark password-protected PDFs?

No. Encrypted PDFs are not supported. Remove the password first, then add the watermark.