Add Watermark to PDF

How to use

1. 1Drop a PDF onto the upload area or click Choose file. Files up to 200 MB work, and the file is read in your browser and never uploaded.
2. 2Type the watermark text or pick a preset such as CONFIDENTIAL or DRAFT.
3. 3Choose a placement (diagonal, tiled, or horizontal), then set the font size, opacity, angle, color, and bold. The live preview updates as you change them.
4. 4Press Add watermark to build the new PDF in your browser.
5. 5Download the watermarked PDF, or use Copy summary to grab a short note of what was applied.

About this tool

Add Watermark to PDF stamps a text watermark onto every page of a PDF and writes a new, downloadable file with the watermark baked in. It reads your PDF with file.arrayBuffer(), indexes every object in place, walks the page tree, and adds the watermark as a separate overlay layer on top of each page so your original text, images, and vector graphics are never altered. You control the watermark text (with quick presets like CONFIDENTIAL, DRAFT, COPY, SAMPLE, and DO NOT COPY), the placement (a single diagonal label across the center, a single horizontal label, or the text tiled to repeat across the whole page), the font size in points, the opacity from faint to solid, the rotation angle for diagonal and tiled layouts, the color, and whether the text is bold. A live preview shows roughly how the watermark will sit before you build anything. Opacity is applied with a real PDF graphics state (an /ExtGState with the fill and stroke alpha set), so the watermark stays readable while the page content shows through underneath rather than being painted over. The text is drawn with Helvetica or Helvetica-Bold, two of the Standard 14 fonts that every PDF reader is required to render without embedded font data, so the output stays small and looks identical in Chrome, Firefox, Safari, Adobe Acrobat, Preview, Edge, and Foxit. Placement is computed against each page's own MediaBox and rotation, both of which are inheritable down the page tree, so mixed-orientation documents and pages that were already rotated still get an evenly placed, upright watermark. The output is re-emitted as a clean, self-contained PDF: a fresh catalog and pages root, every carried object renumbered into a contiguous range with its indirect references rewritten, one shared font object, one shared graphics-state object, and one small overlay content stream per page, with all existing stream payloads (image data, embedded fonts, content streams) copied byte-for-byte and never decompressed so visual quality matches the source. Encrypted (password-protected) PDFs and PDFs that store their page tree inside compressed object streams (PDF 1.5+ /Type /ObjStm) are detected and rejected with a clear message rather than producing a broken file. Bookmarks, the structure tree, and form fields are not carried over because they reference pages by absolute identity in the source; annotations attached to a page travel with that page. Everything runs locally on your device, so the PDF you watermark and the file you download never leave your browser.

Free to use. Works in your browser. No signup, no login.