PDF watermark
Add a text or logo watermark to every page: position, anti-theft tiling, opacity and rotation, optionally only the pages you list
把 PDF 拖到这里，或点击选择
一次处理一个文件；水印会写进新文件，原文件不受影响
PDF 加水印的常见用法
标注用途与来源。「仅供 XX 使用」「内部资料」「禁止外传」这类文字水印能有效降低文件被随手转发、冒用的概率；把公司 Logo 放在页面角落则用于署名与品牌露出。位置建议放在下中或右下——不遮挡正文，又不易被裁掉。
平铺水印是防盗用的关键。单点水印只要裁剪页面就能去掉，平铺（铺满整页）会让裁剪后仍留有痕迹，适合合同、报价单、方案这类敏感文件。代价是页面可读性下降，建议把透明度压到 15%~25%。
透明度与旋转怎么配。45° 倾斜 + 20% 左右透明度是最常见组合：既明显又不喧宾夺主。彩色 Logo 建议透明度更低一些（10%~15%），避免覆盖正文。若要覆盖扫描件（底色复杂），把透明度提到 30% 以上或改用白色描边效果更清晰——本工具对文字水印自带描边。
关于隐私与合规。水印在你的浏览器里绘制并写入新 PDF，文件不上传任何服务器（可在开发者工具 Network 面板核验）。给非本人所有的文件加水印时请注意：修改他人文件的版权信息可能涉及法律风险，请确保你有权处理该文件。
FAQ
Not with this tool. The watermark is drawn into the page content; to remove it completely you have to go back to the original file without the watermark - so please keep the original.
Slightly: a text watermark is embedded once as a transparent PNG and referenced by every page; a logo watermark depends on the image size. Usually it adds only tens to hundreds of KB.
Because the text is first painted into an image with a system font inside the browser, then embedded into the PDF as an image - so it is not bound by the PDF built-in fonts' lack of Chinese support, and every character except emoji displays fine.
Yes. The watermark is a separate layer drawn over the page content, so it works just as well on scans (whose pages are whole images).
A PDF with an opening password cannot be parsed - please remove the password in a reader and save a copy first, then process that.