Merge PDF files
Join several PDFs into one, in the order you add them.
Processed in your browser. This file is converted on your device and is never uploaded.
Converter
.pdf up to 100 MB each. You can also drag files here.
No file selected.
About this tool
Combining a covering letter, a report, and an appendix into one document is one of the most common things anyone needs a PDF tool for, and it is also the thing people most often do by uploading confidential files to a stranger's server. This tool joins them in your browser instead.
Documents are merged in the order they appear in the file list, and every page is copied across unchanged.
Supported formats and limits
- Input
- Output
- .pdf (application/pdf)
- Output name
- Always merged.pdf.
- File size limit
- 100 MB
- Processing
- In your browser. The file is not uploaded.
How to use it
- Choose two or more .pdf files. They are merged in the order listed.
- Remove any file you added by mistake.
- Select Convert, then download merged.pdf.
Limitations
- Interactive features do not survive reliably. Form fields, digital signatures, and JavaScript actions are not carried across, and a signature would be invalidated by the merge in any case.
- Bookmarks, the document outline, and internal links between pages are not preserved.
- Attachments and file-level metadata are not carried over.
- Password-protected documents cannot be opened.
- Every document is held in memory at once, so merging several large files can exhaust a phone.
- Page sizes are kept as they are, so mixing A4 and Letter produces a document with pages of both sizes.
Common problems
The file was refused before anything started.
Merge PDF files checks the extension before it reads a byte, and it accepts .pdf. Browsers report file types inconsistently enough that the extension is what decides.
Rename the file if the extension is simply wrong, or convert it to one of those first. A file whose extension does not match its contents is refused for the same reason, and that one needs converting rather than renaming.
It said the file was too large.
The limit here is 100 MB. It is not a policy but a measurement: everything runs on your own device, and past that size a phone runs out of memory rather than finishing slowly.
Split the file, reduce it before converting, or use a desktop program for that one. A machine with more memory will manage more, but the limit does not know which machine it is on.
Nothing happened for a long time on the first run.
Merge PDF files downloads a library before it can begin, and it is fetched once and then reused. That wait is before the conversion rather than during it, which is why the progress bar sits still.
Leave the tab open and in the foreground; a background tab is throttled by the browser. Every conversion after the first one in a session skips this.
The tab reloaded itself part-way through.
The browser ran out of memory and restarted the page. At sizes approaching 100 MB this is the failure a phone hits first, and it looks like a crash rather than an error.
Try a smaller file, close other tabs, or run it on a computer. Nothing was uploaded or lost — the original file is untouched on your device.
The result opened in the wrong program.
The output is a .pdf file, and your system opens that extension with whatever it was told to. Nothing about the conversion decides it.
Open it from inside the program you want, or change the default for .pdf in your system settings. The file itself is correct.
Frequently asked questions
- Are my documents uploaded?
- No. The merge runs entirely in your browser. The documents never leave your device and no request carrying them is made.
- How do I control the order?
- Files are merged in the order shown in the list. Add them in the order you want, or merge and then use the reorder tool.
- What happens to signatures?
- They are lost. A digital signature covers the exact bytes of the document it signed, so any edit, including a merge, invalidates it. Merge first, then sign.
- Can I merge a password-protected PDF?
- No. Encrypted documents are refused. Remove the password in a PDF reader first.
- Do I need to install anything or create an account to use Merge PDF files?
- No, to all of it. Merge PDF files runs inside the browser you already have, with no sign-up, no download, no watermark on the result, and no cap on how many files you convert. There is nothing to uninstall afterwards either, because nothing was installed.
- Does Merge PDF files work offline?
- Once the page has loaded, yes. The conversion runs on your device, so it needs no connection to do the work. The first visit fetches the page and the code that does the converting; after that a lost connection stops nothing, and a converted file appears exactly as it would online.
- How large a file can Merge PDF files handle?
- The limit is 100 MB. It is a deliberate one rather than a technical ceiling: the real constraint is memory, and a file that decodes to more than the device can hold fails in a way that is hard to explain. Phones run out well before laptops do, which is why the limit is set where it is.
- Can I convert several files at once with Merge PDF files?
- Yes. Choose or drag as many as you like and they are converted one after another, then handed back together. They are processed in sequence rather than all at once, because running several conversions in parallel is the fastest way to exhaust the memory of a phone.