PDFに透かしを追加 – 無料オンライン

Add watermark to PDF — free, online, no upload

Add a text watermark to your PDF for branding, confidentiality marking, or draft labeling. This tool stamps your custom text diagonally across every page with adjustable size, opacity, and angle. All processing stays in your browser — no upload to any server.

Common watermark use cases

• CONFIDENTIAL — mark internal documents before sharing externally.
• DRAFT — clearly label work-in-progress versions.
• Company name — brand your PDFs before sending to clients.
• DO NOT COPY — discourage unauthorized redistribution.
• Your name/email — watermark portfolios and creative work.

How it works

1. Upload your PDF.
2. Enter your watermark text, adjust size (12-144pt), opacity (5-50%), and angle (-90° to 90°).
3. Click Add Watermark.
4. Download the watermarked PDF.

Privacy

Your PDF never leaves your browser. All watermarking is done locally using pdf-lib. Safe for sensitive and confidential documents.

Why watermark a PDF

Watermarks signal status (DRAFT, CONFIDENTIAL, INTERNAL ONLY), ownership (your company name or logo), or copyright (© 2026 …). Adding the watermark inside the PDF means every reader sees it, every print copy carries it, and casual screenshots remain attributable to you. Adding it as an overlay outside the document is fragile because the recipient can simply strip it.

Text or image watermarks

This tool supports both text watermarks (set your own message, font size, color, opacity, rotation angle, and position) and image watermarks (upload a logo PNG with transparency for a more polished, branded effect). Apply to every page, or only specific pages.

Use cases

• Draft markers — large diagonal DRAFT or WORK IN PROGRESS across every page during review.
• Brand stamping — your logo subtly in the corner of every proposal or whitepaper you send.
• Copy protection — visible CONFIDENTIAL or NOT FOR DISTRIBUTION on legal or financial reports.
• Sample previews — DEMO or SAMPLE across pages of a paid template before purchase.
• Author attribution — academic photo credits or your own copyright notice.

Watermark design tips

• Use 20–40% opacity so the watermark is visible without obscuring text.
• Diagonal (45°) text watermarks are harder to crop out than horizontal ones.
• For logos, keep the file under 200 KB and at least 600 px wide for sharp print rendering.

Complete PDF workflow with ToolAtom

This is one of ToolAtom's PDF tools. They all run in your browser with no upload, so you can chain them safely on confidential documents. Common workflows: scan or merge → rotate → add page numbers → watermark → protect, or unlock → edit metadata → re-protect for the next recipient.

• Rotate PDF — Fix the orientation of pages.
• Add Page Numbers — Number every page for printing or filing.
• Protect PDF — Encrypt with a strong password before sharing.
• Unlock PDF — Decrypt a PDF whose password you know.
• PDF Metadata Editor — Clean up title, author, and keywords.
• PDF to Text — Extract plain text for analysis or accessibility.
• PDF to JPG — Render pages as images for slides or thumbnails.
• PDF Merger — Combine multiple PDFs into a single file.
• PDF Splitter — Break a large PDF into smaller files.
• PDF Compressor — Shrink file size for email and upload.

Related tools

People using this tool often also use Protect PDF, Add Page Numbers to PDF, Rotate PDF, and PDF Metadata Editor.