日本語English

Sign & Stamp PDF

Add handwriting, Japanese-style seals (round, square, date), images or text to a PDF at real size in millimetres. It is a visual mark, not a certificate-based digital signature, and your PDF never leaves your device.

On-device・No upload

Your files and input are processed only inside your browser on this device and are never uploaded to our servers.

Drop a file here

or

PDFs are processed in this browser on your device and never uploaded.Accepts: PDFUp to 300 MB per filePaste (Ctrl+V) also works

How to use

  1. Drop a PDF or click “Choose files”. “Try a sample” lets you test it right away.

  2. Make a stamp on the right: “Seal” for round, square and date seals, “Handwriting” for a signature, “Image” for your own scan, “Text” for a name or “Approved”.

  3. Press “Place on this page”, then drag to move, drag a corner ■ to resize and the ● above to rotate. “Place on all pages” puts it at the bottom right of every page.

  4. Under “Pages to stamp” switch between all pages, this page, or a custom list (e.g. 1, 3-5, odd). You can also type the width in mm.

  5. Press “Stamp and create PDF”, check the re-rendered result in the preview, and download.

What it does

Real size in millimetres

Round, square and date seals are made at around 10–30 mm and converted with 1 mm = 72 ÷ 25.4 pt. Resizing on the page keeps the aspect ratio and always shows the current real size in mm.

Correct on rotated and cropped pages

Coordinates account for the page’s /Rotate (0, 90, 180, 270°) and for MediaBox / CropBox origins that are not (0, 0), so a stamp lands exactly where you see it.

Exported as 300 dpi-class images

Stamps are embedded as transparent PNGs on the chosen pages, up to 300 dpi for their size on the page and never enlarged beyond the source bitmap. The original page content is kept and the stamp is laid on top.

Handwriting with pressure or speed

Pens vary the line by pressure; fingers and mice by writing speed. Black or navy ink, undo last stroke, clear all, and the background stays transparent.

Image import with white removal

Load a photo or scan of a seal or signature (PNG / JPEG) and make the white background transparent with a threshold. Soft edges keep faint seals from breaking up.

Save on this device

Only stamps you explicitly save are kept in this browser’s localStorage. Delete them one by one or all at once; nothing is sent to a server.

Use cases

  • Put an approval seal or date stamp on a document that circulates for sign-off
  • Lay a company seal image over an invoice or quotation
  • Stamp a confirmation seal at the bottom right of every page of a draft contract
  • Photograph a seal or signature on paper, remove the white background and place it on a PDF

Supported formats

Input

PDF (.pdf)Seal / signature images (PNG, JPEG)

Output

PDF (.pdf)

Capability matrix

FeatureSupportNotes
Handwritten signature (pen, touch, mouse)SupportedLine width follows pressure or speed
Round, square and date seals at real size (mm)Supported—
Image import (PNG / JPEG) with white background removalSupported—
Text such as name, date, “Approved”SupportedStamped as an image, so the text cannot be selected or searched in the PDF
Several stamps; all pages or chosen pages at onceSupported—
Correct placement on /Rotate and CropBox pagesSupported—
Seal typefaces such as tenshoPartialDrawn with your device’s Mincho / Gothic fonts; a tensho seal can be imported as an image
Warikan (a seal straddling two pages)PartialThe same seal can go on every page, but straddling a page boundary is not supported
Certificate-based digital signature (PAdES) and timestampsNot supported—
Tamper detection and signer identityNot supported—
Keeping an existing digital signature validNot supportedSaving rewrites the PDF, which invalidates existing signatures
Flattening form fieldsNot supported—
Password-protected PDFsNot supported—

Limits & notes

  • PDFs up to 300 MB. Seal / signature images up to 20 MB (the longer side is reduced to 1600 px).
  • Round seals take 1–4 characters, square seals up to 4 lines of 8 characters, date stamps 8 characters of department and 6 of name.
  • Text stamps take up to 5 lines of 30 characters. Imported images up to 36 megapixels.
  • Japanese typefaces come from fonts installed on your device, so the look varies by device.
  • Password-protected PDFs cannot be opened.
  • Stamps become images and cannot be edited in the exported PDF.

Privacy & safety

Viewing, making stamps, stamping and saving all happen in your browser; neither your PDF nor your stamps are sent to a server. Only stamps you explicitly save are stored in this browser’s localStorage, and you can remove them with the delete buttons or by clearing site data.

FAQ

How do I put a hanko (seal) on a PDF?
Open the PDF, make a round, square or date seal in the “Seal” tab and press “Place on this page”. Drag it into position, adjust the size with a corner ■, then press “Stamp and create PDF” and download. To use a scanned seal, import it in the “Image” tab.
Does this have legal effect? How is it different from a digital signature?
It only draws the look of a signature or seal onto the PDF. It is not a certificate-based digital signature (PAdES etc.): it cannot prove who signed or detect later changes, and anyone could reproduce the same image. Legal treatment depends on the type of agreement and on how the parties agree to use it. For important contracts, agree on a method with the other party and use a digital-signature service where needed.
Will the seal print at its real size?
Yes. The size you set in millimetres is converted to PDF points, so printing at 100% gives that size. “Shrink to fit” printing shrinks it accordingly.
What about scanned PDFs that are rotated or cropped?
The page’s /Rotate (0, 90, 180, 270°) and visible-area (CropBox) offset are taken into account, so the stamp lands where you see it. The exported PDF is rendered again in the same view so you can verify it.
Can I stamp the same place on every page?
Yes. “Place on all pages” puts it at the bottom right of each page, and “Pages to stamp” lets you switch to this page only or a list such as 1, 3-5, odd later. Pages of different sizes use the position relative to the page.
Can I reuse my stamps? Is my PDF uploaded?
Stamps you save with “Save on this device” are kept in this browser (localStorage) and can be deleted at any time. Your PDF and stamps are never uploaded. Do not save on a shared computer.

Related tools

Images to PDF

Drop images, put them in order and get one PDF. Choose page size, orientation and margins; phone photos are rotated correctly. Images are converted on your device and never uploaded.

Compress PDF

Drop a PDF to cut its size. Only photos and scans are recompressed, so text and graphics stay crisp. Your PDF is processed on your device and never uploaded.

PDF Editor

Lay text (Japanese included), shapes, arrows, a highlighter, freehand drawing and images on top of a PDF, and fill in its form fields. Everything is written as PDF vectors and real text, never as a picture. Rewriting the original text and true redaction are not possible.

PDF Extract

Take the text, images, links, attachments, form values and bookmarks embedded in a PDF, for the pages you choose. Images stay as embedded (JPEG untouched). Your PDF never leaves your device.

Extract PDF Pages

Gather just the pages you need from one or more PDFs into a single PDF (or one PDF per source file in a ZIP). Pick by thumbnail, range or text search, and leave out blank pages automatically. Your PDFs are processed on your device and never uploaded.

Merge PDF

Drop several PDFs, put them in order, and get one PDF. You can also choose which pages to take from each file. Nothing is uploaded — merging happens on your device.

Last updated: