PDF n-up printing / N pages per sheet
Shrink 2 / 4 / 6 / 9 pages onto one sheet (handouts and exam papers), with the text layer fully preserved
把 PDF 拖到这里，或点击选择
一次处理一个文件；原文件只被读取，导出的是一份新 PDF，原始文件不会被修改
文件不会上传到服务器：读取、拼版与生成新 PDF 全部在你的浏览器里完成
PDF 拼版（N 合 1）的常见场景与取舍
典型场景：讲义、试卷、手册、合同附件。N 合 1 就是把连续几页缩到一张纸上：4 合 1 把 4 页排进 1 张 A4，6 合 1 排 6 页，9 合 1 排 9 页。常见用法是课件讲义缩印带进课堂、给学生印试卷或练习题（一页纸多道题，方便对照）、把长合同与附件拼成便携版。留白较多的文档效果最明显；字本来就很小的资料，不要一次缩太多页。
为什么「嵌入页」比「截图拼版」好。本工具用的是 PDF 的页面嵌入机制（Form XObject）：把源页作为完整的页面对象画到新纸上，页面里的文字、矢量图形与字体都不重新光栅化。两个直接好处是——拼接后文字仍然可以搜索、复制、选中，放大打印也不发虚；输出体积接近原文件，不会因为「把每页转成图片」而暴涨。另一种常见做法是先把每页渲染成图片再拼成新 PDF，那会把文字层彻底丢掉，画面细节变成位图，体积还可能反而变大。
A4 还是 Letter，纵向还是横向。国内打印一律选 A4；Letter（216 × 279 mm）主要在美国、加拿大使用，比 A4 宽一点、短一点，直接打在国内的 A4 纸上会两边缺一点。2 合 1 要按内容方向选：上下排（纸张纵向）适合两页纵向文档叠印，左右排（纸张横向）适合把两页横向的幻灯片并排在一张纸上。6 合 1（2×3）与 9 合 1（3×3）都用纵向纸；源页如果自带旋转，会按旋转后的视觉方向自动转正再缩放，不会被压扁。
缩小后字太小怎么办、为什么不上传。4 合 1 之后每页只剩原来的四分之一，原本 10.5pt 的正文会变成 5pt 左右，肉眼会很吃力：可以把源文档改成更大字号或分成两栏再拼，或者把格数降到 2 合 1。整份拼版都在你的浏览器里完成（用 pdf-lib 在本机内存里生成新 PDF），过程中没有任何文件上传请求——可以打开浏览器开发者工具的 Network 面板核验，合同、试卷、证件扫描件这类材料不必离开你的电脑。
FAQ
Yes. Each source page is drawn onto the new sheet as an embedded page object (Form XObject); text and vector graphics are not re-rasterized, so the imposed PDF stays searchable, copyable and selectable with the same quality as the original. The one exception: a source page that is itself a scanned image never had a text layer - imposition will not conjure text out of it (this tool does no OCR). Also note honestly: links, annotations and form fields belong to the page objects, not the page content, and are not preserved when embedding.
Because embedding writes each page's referenced resources into the new file: if many pages share one font or one logo, every embedded page carries it along - the more pages and the bigger the fonts, the more visible. It is the normal price of keeping the text layer instead of re-rasterizing. The tool embeds all pages in one batch (pdf-lib deduplicates shared resources within a single batch call), which keeps duplication to a minimum; the size report states truthfully whether the file grew or shrank and why - it never pretends success. If size matters, run the result through our PDF compression page afterwards.
The last sheet leaves its empty slots blank - no blank filler pages and no lost pages: 3 pages in 4-up produce 1 sheet (1 slot empty), 5 pages in 4-up produce 2 sheets (the second has 3 empty slots). The page math is simply ceil(pages / slots per sheet). The result report lists, sheet by sheet, which page went into which slot.
Small type is the inevitable consequence of scaling: try dropping to 2-up, shrinking the outer margin and the gap so cells grow, or re-exporting the source with a larger font. Wrong orientation usually means the wrong paper direction: portrait documents stack better top-bottom, landscape slides side-by-side; when a source page carries its own rotation (/Rotate 90 or 270) the tool reads its visual width and height and rotates it upright - landscape pages do not get squashed. If the print comes out upside down, check the printer's duplex/page-turn setting - not the imposition.
A PDF with an open password cannot be parsed by the browser, so this tool cannot process it either - open it in a reader and Save As an unencrypted copy first, then impose that. The original stays on your computer throughout: the tool reads a copy in browser memory only, exports a brand-new file, clears memory when you switch files, and there is no file-upload request at any point.