Stamp Multiple PDF Files Online
Batch-add a signature, seal, or watermark image to multiple PDFs at once. Everything runs inside your browser — files are never sent to any server.
100% client-side — your files never leave this device
Step 1 — Add PDF files
Drop PDFs here or click to browse
Multiple files supported — no size limit
Step 2 — Choose stamp image
Drop stamp / signature image here or click
PNG (with transparency) or JPG
Step 3 — Position & size
PDF coordinates: origin = bottom-left. Leave blank to use the preset above.
Height scales proportionally. A4 page width ≈ 595 pt, US Letter ≈ 612 pt.
100%
Step 4 — Which page(s) to stamp
Starting…
How it works
This tool uses pdf-lib (a pure-JavaScript PDF library) and JSZip entirely in your browser tab. Here is what happens when you click the button:
1Read filesEach PDF and the stamp image are read from your local disk into memory as ArrayBuffers — no network request is made.
2Embed stamppdf-lib embeds the PNG/JPG into each PDF document as an image XObject at the coordinates and size you chose.
3Draw on pagesThe image is drawn on the selected pages (all, first, last, or specific numbers) using a PDF graphics operator with your chosen opacity.
4ZIP & downloadAll stamped PDFs are collected by JSZip and compressed into a single .zip file that is saved directly to your Downloads folder.
PDF coordinate units are points (1 pt = 1/72 inch). The origin (0, 0) is the bottom-left corner of each page, so Y increases upward — this is the native PDF coordinate system. Preset positions (top-right, center, etc.) are calculated automatically from each page's actual dimensions.
Frequently asked questions
- Are my PDF files uploaded to a server?
- No. Every operation — reading files, embedding the stamp image, generating the output ZIP — runs entirely inside your browser using JavaScript. Nothing is transmitted over the network. You can even disconnect from the internet after the page loads and the tool will still work. This makes it safe to use with confidential documents such as contracts or medical records.
- What image formats can I use as a stamp?
- This tool supports PNG and JPG/JPEG images. PNG is strongly recommended when your stamp or signature has a transparent background, because the transparency will be preserved in the final PDF. JPG images are fully opaque and will show a white or solid background behind the stamp. SVG is not supported because pdf-lib works with raster images — if you have an SVG stamp, export it as a high-resolution PNG first (at least 300 DPI for print quality).
- How do I stamp only the last page of each PDF — for example, a signature page?
- Select "Last page only" in Step 4. The tool automatically detects the last page of each individual PDF file, so if you have a mix of 2-page and 10-page documents, the stamp is placed on page 2 of the first and page 10 of the second. Use "Page numbers" if you need more control — enter comma-separated page numbers (1-based), and pages beyond any document's length are skipped automatically.
- What do the position and size numbers mean?
- PDF dimensions are measured in points (pt), where 72 pt = 1 inch. A standard A4 page is 595 × 842 pt; US Letter is 612 × 792 pt. The stamp width slider controls how wide the image will be; the height is scaled proportionally to preserve the aspect ratio of your original image. The X and Y coordinates measure the bottom-left corner of the stamp from the bottom-left corner of the page. The preset buttons (Top right, Center, etc.) compute these values automatically based on each page's real size.
- Does this work with password-protected or encrypted PDFs?
- No. Encrypted or password-protected PDFs cannot be modified without decryption. If you try to stamp an encrypted PDF, that file will be skipped and an error will appear in the status area. Decrypt the PDF first (using the owner password) before using this tool. The remaining files in your batch will still be processed normally.
- Is there a limit on the number of files or file size?
- There is no hard limit imposed by this tool — the only limit is your browser's available memory. For very large batches (50+ files) or very large individual PDFs (100 MB+), processing may be slow. Modern browsers can typically handle several hundred megabytes of data in memory. If your browser tab crashes, try processing files in smaller batches.