PDFにオンラインで署名 - ブラウザで無料でPDFに署名を追加

PDFをアップロードし、装飾的な署名を入力するか、マウスや指で描くか、スキャンした署名の透明PNGをアップロードします。それを署名フィールドにドラッグし、余白にイニシャルを加えてから、どのビューアでもきれいに開ける署名済みPDFをダウンロードできます。

ほとんどの法域では有効です——米国のESIGN法、EUのeIDAS、英国の電子通信法、インドのIT法はいずれも、日常的な契約（雇用オファー、NDA、業務委託契約、請求書など）における単純な電子署名を認めています。高額な取引には、適格電子署名が求められる場合があります。

はい。各署名者用の署名欄を追加し、一部署名済みのPDFを保存して次の署名者に送れば、割り当てられた欄に署名してもらえます。誰がいつ署名したかという監査証跡はPDFのメタデータに埋め込まれます。

ツールバーから署名、イニシャル、日付スタンプを任意のページにドロップします。日付スタンプはデフォルトで今日の日付を使いますが、変更も可能です。ダウンロード時にPDFをフラット化すれば、受信者が署名の配置を変更できなくなります。

Page previews render locally, but signing itself happens on our secure server: your document and signature image are uploaded over HTTPS, stamped into the PDF there, and deleted automatically afterwards — we never store or share them. That works well for everyday paperwork like employment contracts and NDAs; if your policy requires a signer that never uploads the file at all, use an offline desktop PDF tool instead.

はい。「ダウンロード時にフラット化してロック」をオンにすると、署名、イニシャル、日付スタンプがページに焼き込まれます。任意のパスワード保護のステップと組み合わせれば、文書は改ざんが検出できる状態になります。

このツールは電子署名 — 手書き・入力・アップロードした署名の目に見えるイメージをページに押印するもの — を追加します。NDA、オファー、請求書といった日常的な契約では法的に有効です。証明書ベースのデジタル署名（Acrobatが.p12 / PKI証明書と照合する暗号方式のもの）は作成しません。通常の文書には電子署名で十分ですが、暗号的に改ざん検証が必要な書類には、証明書ベースの署名サービスをお使いください。

このツールは、ページの好きな場所に配置する署名・イニシャル・日付・スタンプに特化しています。PDFに入力すべき対話型のフォームフィールド（チェックボックス、テキスト入力、ドロップダウン）がある場合は、まずPDFフォーム入力ツールで記入し、その後ここに戻って署名を追加してください。

Yes — switch to the Text tab and type your paragraph, then pick a font family (Sans, Serif, Mono or Handwritten), a text color, and drag the size slider to set how large it renders on the page. Bold and italic toggle buttons next to the size slider let you emphasize the text without leaving the tool.

In the Signature tab, choose the Type mode, enter your name, then pick from eight cursive font styles — Caveat, Dancing Script, Great Vibes, Sacramento, Allura, Pacifico, Homemade Apple or Kalam — shown as live previews of your own name. Each renders a different handwriting look, so you can match the tone of the document you're signing.

Open the Date tab, pick a day with the date field or tap Today for the current date, then choose a format from the dropdown — MM/DD/YYYY, DD/MM/YYYY, YYYY-MM-DD, Month DD, YYYY, or DD Month YYYY. The live preview under the format picker shows exactly how the stamped date will look before you place it, and you can still adjust its font, color and size like the text tool.

Yes — in the Stamp tab, choose Create mode and enter your company name plus a short line like APPROVED, PAID or DRAFT; the tool generates a circular stamp graphic in the color you pick with the color field. If you already have a real company stamp image, switch to Upload mode instead and use that PNG or JPG directly.

Use the Signature tab (Type mode with a cursive font, or Draw if you prefer your real signature) to place your name, then switch to the Date tab and pick a format like Month DD, YYYY with Today selected for a professional-looking date stamp. Finally, add a Stamp in Create mode reading APPROVED in your brand color to mark the document reviewed — all three can be dragged and resized independently on the same page before you download.

In the Signature tab, choose Draw mode and sign directly on the canvas with your mouse, trackpad or a finger/stylus on touchscreens. If it doesn't come out right, tap Clear underneath the canvas to wipe it and try again — the tool automatically trims the transparent border around your ink so the signature drops onto the page at the right size.

Drag anywhere on a placed item to move it, or drag the small handle at its corner to resize it — text and date items automatically scale their font size as you resize. On a touchscreen you can also pinch with two fingers to resize and reposition in one gesture, and pressing Delete or Backspace removes whichever item is currently selected.

Yes. Use the Prev/Next arrows or the page thumbnail strip to jump between pages — each thumbnail shows a small badge with how many items you've already placed on it. The Placed signatures list in the Pages panel lets you tap any item to jump straight back to its page and select it, or delete it from there.

Once your PDF finishes rendering, a one-time popup asks for your full name (pre-filled if you're signed in) and, when you confirm, instantly builds a typed cursive signature from it and switches you to the Signature tool so you can tap the page to place it immediately. Tap Skip if you'd rather draw your signature or upload an image instead.

Switch to the Stamp tab, then either use Create mode to type your company name and a short line of text like APPROVED, PAID or DRAFT and pick a color — the tool renders it as a circular stamp graphic on the spot — or switch to Upload mode to drop in an existing PNG or JPEG of your company's real rubber stamp. Once it's rendered or uploaded, tap Add to page (or tap anywhere on the document) to place it just like a signature.

Yes — the Text tab is separate from Signature, Date and Stamp and lets you type a full paragraph (for example a certification statement or a note to the recipient) into a textarea. You can pick one of four fonts (Sans, Serif, Mono or Handwritten), set a color with the color picker, adjust size with the 1-6% slider, and toggle Bold or Italic before placing it on the page.