Merge PDF.合并 PDF。

Merge PDF on StayFile takes two or more PDFs and copies their pages, in the order you set, into one new file. The download is named stayfile-merged.pdf. This is a free page from Haimc (海明创). There is no account, no trial banner stamped on the pages, and no step that posts the documents anywhere. You add the files, move a row up or down until the reading order is right, and the browser saves the result.

StayFile 的合并 PDF 把两份或更多 PDF 的页面，按你排好的顺序，复制进一个新文件。下载文件名叫 stayfile-merged.pdf。这是海明创（Haimc）的一个免费页面。没有账号，页面上也不会被盖上试用横幅，更没有把文档发出去的那一步。你添加文件，把某一行上移或下移，直到阅读顺序对了，再由浏览器保存结果。

The work stays in this tab. Choosing or dropping a PDF reads its bytes into memory and counts the pages with pdf-lib, which runs in the page. The list shows that count. Files added together land in the order the browser hands them over. The up and down buttons change that order. There is no drag-and-drop reorder, and every page of one file stays together. The Merge button stays off until at least two files are ready and none of them failed. pdf-lib then opens each document and copies every page into a new document. Clear the list, or close the tab, and the copies held in memory go with it. A file you already saved is an ordinary download. StayFile does not keep a copy of it.

处理留在这个标签页里。选择或拖入一份 PDF 时，字节被读进内存，页数由页面里的 pdf-lib 数出来。列表会标出这个页数。一次加进来的文件，按浏览器交给页面的顺序往下排。上移和下移按钮用来改这个顺序。这里不能拖拽排序，同一份文件里的页面也会整份待在一起。至少有两份文件准备好，并且没有一份失败，合并按钮才会亮。然后 pdf-lib 打开每一份文档，把所有页面复制进一份新文档。清空列表，或关掉标签页，内存里的副本就一起丢掉。你已经保存的文件只是一次普通下载。StayFile 不会留着它的副本。

The ceilings keep one tab from holding an unbounded job. One run accepts at most 30 files, 400 pages in total, and 80 MB for any single file. Drop more than 30 at once and the extras are not added. A password-protected PDF, a file that is not a PDF, a damaged file, a file with no pages, or a file over 80 MB stays in the list with an error. The merge cannot run until you remove that row. StayFile does not ask for the password and does not send the file out to be unlocked. A phone can open this page in its browser. There is no app to install. A packet that is comfortable on a laptop can still run out of memory on a phone, because the bytes live in the tab until you clear them.

这些上限是为了不让一个标签页接下没有边际的活。一次最多 30 个文件、合计 400 页，单个文件不超过 80 MB。一次拖进超过 30 个时，多出来的不会被加进列表。有密码的 PDF、不是 PDF 的文件、损坏的文件、没有页面的文件，或超过 80 MB 的文件，会留在列表里并标出错误。你把那一行移除之前，合并不能开始。StayFile 不会向你要密码，也不会把文件送出去解锁。手机可以用浏览器打开这个页面。没有需要安装的应用。在笔记本上还轻松的一批文件，在手机上仍可能把内存用完，因为这些字节会留在标签页里，直到你清空它们。

What comes along is the page: its size, its rotation, and the content drawn on it. A US Letter contract followed by an A4 scan stays Letter, then A4. A sideways scan stays sideways. Text that was stored as text stays selectable, because the page is copied rather than photographed, and a font embedded in that page comes with it. StayFile does not supply a font the source left out, and it does not run OCR, so a scan that was already a picture stays a picture. The new file does not rebuild the bookmark outline, file attachments, document scripts, or document info such as title and author. The look of a comment or a form may still sit on the page. A cryptographic signature on a source does not remain a valid signature of the new file. Open the download and try the field, the link, or the signature check before you send it.

跟着走的是页面本身：尺寸、旋转，以及画在上面的内容。一页 US Letter 合同后面接一份 A4 扫描件，合并后仍是先 Letter、后 A4。横着的扫描件还是横着的。原来以文字保存的内容仍然可以选中，因为这里是复制页面，不是把页面拍成图片；嵌在那一页里的字体也会一起复制过来。源文件没嵌的字体，StayFile 不会补上。这里也没有 OCR，本来就是图片的扫描件，合并后还是图片。新文件不会重建书签目录、文件附件、文档脚本，以及标题、作者这类文档信息。批注或表单的样子可能还留在页面上。源文件上的数字签名，不会变成新文件的有效签名。发出去之前，先打开下载文件，试一下字段、链接，或签名校验。

Leave this tool when the job is a different one. It will not turn a PDF into Word or a spreadsheet, will not make a scan searchable, will not remove or apply a password, will not force every page onto one paper size, and will not repair a file that will not open. If a contract’s digital signature has to stay valid, merge a reading copy and keep the signed original untouched. If you only need a few pages from one file, use Split. If you need a smaller file and can accept a picture of each page, use Compress. Past 30 files or 400 pages, merge a batch, then merge that download with the next batch.

要做的事如果是另一件，就不要用这个工具。它不能把 PDF 转成 Word 或表格，不能让扫描件变得可搜索，不能去掉或加上密码，不能把每一页都改成同一种纸张，也不能修复打不开的文件。如果合同上的数字签名必须仍然有效，请只合并一份用来阅读的副本，签过名的原件留在原地。如果只是要从一份文件里抽出几页，用拆分。如果需要更小的文件，并且可以接受每一页变成图片，用压缩。超过 30 个文件或 400 页时，先合并一批，再把那份下载和后面一批合在一起。

StayFile does not check that you have the right to combine the files. Password-protected PDFs are refused. Outlines, attachments, document scripts, and document info fields are not rebuilt. A cryptographic signature does not stay valid on the new file. Comments and form fields may still be visible; try them before you rely on them. This is not a form editor, a file converter, or an OCR tool. The originals you picked are not replaced on disk.

StayFile 不检查你是否有权把这些文件合在一起。有密码的 PDF 会被拒绝。书签目录、附件、文档脚本和文档信息字段不会重建。数字签名在新文件上不再有效。批注和表单字段可能还看得见；先试过再依赖它们。这不是表单编辑器，不是格式转换器，也不是 OCR 工具。你选中的原件不会在磁盘上被替换。

The job runs in this tab: at most 30 files, 400 pages, and 80 MB each. A phone browser can use the file picker, but a large packet can still exhaust that phone. If the tab stalls, clear the list and merge in smaller batches. Closing the tab discards the in-memory copies. It does not delete a download you already saved, and it does not wipe the originals.

这件活在这个标签页里做：最多 30 个文件、400 页，每个不超过 80 MB。手机浏览器可以用文件选择器，但一大包文件仍可能把那部手机的内存用完。如果标签页卡住，请清空列表，分成更小的几批再合并。关掉标签页会丢掉内存里的副本。它不会删除你已经保存的下载，也不会清掉原件。