PDF 签名
手写、输入或拍摄一个签名，把它放到页面上。
这款工具完全在你的浏览器中运行。文件从不上传，你可以在浏览器的网络标签中亲自验证这一点。 亲自验证：打开浏览器的网络标签观察。你会看到一个查询你是否还有剩余任务的小请求，只包含工具名称和一段哈希，绝不会包含文件。
这款工具的作用
This places a picture of your signature on the page and draws it into the document's content, so the recipient cannot pick it up and move it. That is what almost every form, contract and delivery note is actually asking for. It is not a cryptographic signature: it cannot prove who signed or that nothing changed afterwards, and if you need that, Digital signature does it.
For everyday paperwork that asks for a signature and not for a certificate: a rental agreement, a school form, a delivery note, an invoice approval, an NDA that arrived by email. It is also the quickest way to sign something when the alternative is printing it, signing it and finding a scanner.
工作原理
- Drop the PDF onto this page.
- Make your signature: draw it with a finger, stylus or mouse, type your name in a handwriting face, or upload a photograph of one on paper - a photograph has its white background dropped so it sits on the page rather than in a white box.
- Place it where it belongs and drag its corner to size it. Turn on sign every page if the document needs initialling throughout.
- Add the printed name and, if the form expects one, the date. Both are drawn in small grey type under the signature, where a printed signature block puts them.
- Press Sign PDF and the download starts on its own.
A drawn signature is an image, and it carries about the weight ink on paper carries: it shows intent, and it is worth what the surrounding evidence makes it worth - the address it came from, the document it sits on, the fact that you sent it back. Electronic signature law in most places treats that as a signature. What it cannot do is show that the file has not been altered since.
Flattening is on here and off almost everywhere else on this site, for one reason: a signature the recipient can select and drag off the page is not much of a signature. The image is written into the content stream and is already permanent, so flattening exists to fold in whatever form fields and annotations the document carried. The cost is that fillable fields become ordinary page content, so fill the form first and sign last.
A photograph of a signature brings the paper with it. The near-white pixels are dropped to transparency, which stops the signature arriving as a grey rectangle stamped across the text underneath. Dark ink, plain white paper and even light give a clean result; a photo taken in shadow keeps its shadow, because nothing here can tell a grey background from a grey pen stroke.
Around 180 by 60 points sits comfortably in most signature blocks, and that is where the tool starts - a very large signature over dense text looks wrong in print even when it looked right on screen. Both the image and the document stay in your browser, which matters here more than on most tools: how your signature looks is worth protecting on its own.
这款工具做不到的事
- This is not a cryptographic signature. It says nothing about who applied it and cannot detect later changes to the document - use Digital signature when either of those matters.
- Flattening, which is on by default, turns fillable form fields into ordinary page content. Fill the form before signing, or turn flattening off.
- The signature goes on one page or on every page. Placing a different signature on each page takes more than one pass.
- The printed name and date are drawn as plain text below the signature at a fixed size; there is no control over their font or position.
常见问题
- 手写画的签名有法律效力吗？
- 在多数法域，电子签名对普通商业文件是有效的——欧盟的 eIDAS 和美国的 ESIGN 法案都这么规定。有差异的是法院会把什么当作你签署过的证据，而这取决于上下文，而非那张图片本身。契据、遗嘱和某些不动产转让在若干国家被排除在外。
- 这和电子签名有什么不同？
- 这是在页面上画一张图片。电子签名会用私钥对文件的字节计算一个密码学值，让任何阅读器都能显示是谁签的、以及此后是否有一个字节被改动过。如果你的收件人期待 Acrobat 里那个绿色对勾，他们要的是「电子签名」。
- 我可以用手指画签名吗？
- 可以，在触摸屏或触控板上都行，有触控笔的话也能用。如果用鼠标画出来的东西你不愿署上自己的名字，那就改为输入你的名字，它会以手写风格的字体呈现；或者拍一张真实签名的照片上传。
- 我该怎么用签名的照片？
- 在白纸上用深色墨水签名，在均匀的光线下正上方拍摄，然后上传这张照片。接近白色的背景会被去掉，使签名落在页面上，而不是落在一个白框里。阴影经此处理仍会留下，所以光线不好会把那些灰色一并带上。
- 我的签名图片会被上传吗？
- 不会。它在页面里绘制或解码，由 Web Worker 中的 pdf-lib 嵌入 PDF，绝不会离开设备。两次访问之间也不会保存任何东西，所以在共用电脑上，标签页一关就不留副本。