Merge PDF files into a single document

How it works

Pick at least two PDFs — tap or click the box and select them all at once. The documents are joined end to end in list order: the first page of file two follows the last page of file one. Three ordering choices are offered. "The order I picked them in" keeps the list exactly as it was built. "By file name A-Z" compares numbers as numbers, so scan-2 lands before scan-10 — most file managers get that pair the wrong way round. "Reverse order" flips the whole list, which is the shortest fix for a stack that was scanned back to front. The result comes back as one PDF and the result line reports how many files became how many pages, so a missing file is visible without opening anything. If the document is going to be printed on both sides, switch on the blank page option: any document that ends on an odd page gets a blank sheet after it, and the next document starts on a fresh front side. Page content is never redrawn — text stays selectable, signatures and stamps are not recompressed, and a page scanned in landscape stays in landscape. Everything happens inside your browser, so contracts, statements and medical records never leave the machine.

This tool is also known as merge pdf, combine pdf files, join pdf, merge two pdfs into one, pdf combiner, put pdfs together.

What is Merging PDFs?

Merging means placing two or more documents end to end inside a single file. Pages are not redrawn or converted; they are carried over as they are, which is why the text of a merged document stays searchable and the images keep their original quality. The demand for it comes almost entirely from upload forms: a single field is offered and the identity page, the proof of address and the payment receipt all have to arrive as one attachment. Because nothing is recompressed, the size of the result is roughly the sum of the parts.

What is Page order?

Page order decides which document comes first, and it is the detail that costs the most to fix afterwards. Computers do not sort the way people expect: when file names contain numbers, most programs compare them as text, so file 10 is placed before file 2. The A-Z option here compares the numeric part as a number, which puts numbered scans in the order a human would read them. If you are unsure, merge first and check the page count on the result line — a wrong total means a file never made it into the list.

What is Double-sided printing?

Printing on both sides of the sheet creates a quiet problem in merged documents. When a one-page letter ends, the first page of the next document is printed on the back of the same sheet, and two separate records become physically inseparable. The fix is a blank page after every document that ends on an odd page, so each new document starts on a front side. Switch the option on and those blanks are inserted for you; the result line says how many were added, which is also the quickest way to predict the paper count.

When merging is the job

Most of the time the reason is on the other side: an application form offers one upload field, and your identity page, address proof and income statement are three separate files. The same is true of email — one attachment instead of ten also removes any doubt about the order they should be read in.

Scanning is the second common case. Sheet-fed scanners and phone apps often save every page as its own PDF, so a twelve-page contract lands on the desktop as twelve files. Putting them back together in the right order is the only practical way to archive the thing and find it again later.

The third case is work assembled in pieces: a cover page from one program, tables from another, a signature page from a third. Exporting each part to PDF and joining them here is far less trouble than forcing every piece through a single program.

Keeping the order straight

The order is fixed the moment you select the files, and the merge follows it. For anything important, rename the parts 01, 02, 03 before you start — a leading zero sorts correctly everywhere. If the numbers have no leading zero, the A-Z option still gets it right, because the numeric part is compared as a number rather than as text.

After merging, compare the page count on the result line with the totals of the parts. A shortfall means one file never entered the list. If the order came out wrong there is nothing to undo: change the setting and press the button again, since each run starts from the original files.

• Rename parts 01, 02, 03 — a leading zero guarantees the sort
• No leading zeros? Use the A-Z option, which reads numbers as numbers
• Scanned back to front? Reverse order flips the whole list
• Check the page count on the result line against the parts

What happens to size and content

Merging is not a conversion. Pages move into the new document untouched, so text stays selectable and searchable, and scanned signatures are not compressed a second time. A page that was scanned sideways stays sideways; if that bothers you, the rotate tool fixes it without touching quality either.

The size of the result is roughly the sum of the parts. A PDF built from fifty photographs stays heavy after merging, so if an email size limit is the real problem, shrinking the images first solves more than anything done afterwards.

Frequently asked questions

How many PDFs can I merge at once?

There is no fixed limit; the limit is your device's memory. Because the work happens inside the browser, every file is held in memory while it runs. A few hundred megabytes at once can be too much for a phone — in that case merge the files in two batches and then merge the two results.

Are my files uploaded anywhere?

No. The PDFs never leave your device: reading, merging and saving all happen in the browser. Once the page has loaded you can disconnect from the internet and the tool still works, which is the simplest way to check the claim for yourself.

Can I merge a password-protected PDF?

No. When a document asks for a password to open, the tool stops and says so instead of guessing. Open the file in a program that can read it and save an unprotected copy — "save as PDF" or "print to PDF" both work — and merge that copy here.

Can I add Word or Excel files?

No, this tool takes PDFs only. Export the document to PDF from its own program first, then merge it here. For photographs, build a PDF with the JPG to PDF tool and bring that file over.

Do I need the blank page option?

Only if you print on both sides and at least one of your documents has an odd number of pages. Without it, the next document is printed on the back of the previous one's last sheet. With it switched on, blanks are inserted automatically and counted on the result line.