Merge PDF

Combine multiple files into a single PDF quickly and easily.

Free
Private
No limits
No upload

Order of files can be changed by drag and drop

... or drop files here

Files never leave your device

Create bookmarksInsert blank pages

Frequently asked questions

Is it safe to merge PDF files with this tool?

Yes. Merging happens entirely in your browser — your files are never uploaded to a server, so nothing about their contents ever leaves your device.

Can I change the order of the files before merging?

Yes, drag and drop the files into the order you want before you merge them.

Is there a limit to how many PDFs I can merge?

No, there's no limit on the number of files — merge as many PDFs as you like, for free.

Will merging reduce the quality of my PDF?

No. Pages are combined exactly as they are, with no compression or re-rendering, so text and images keep their original quality.

Can I merge a password-protected PDF?

Not directly — unlock it first with our Unlock PDF tool, then merge the unlocked file.

Why is my merged PDF as large as all the originals put together?

Because nothing was thrown away. Pages are copied at full fidelity rather than re-rendered, so the output is roughly the sum of its inputs plus a small amount of structural overhead. That is the correct behaviour for a merge tool — if you need a smaller file, run the result through Compress PDF, which lets you pick the resolution and quality trade-off explicitly.

Can I merge PDFs with different page sizes?

Yes. Each page keeps its original dimensions and orientation, so an A4, a Letter and a landscape page can sit in the same output. Readers handle this without complaint, though a printer may ask how to scale each one.

Do bookmarks and form fields survive?

Form fields and annotations survive, but two fields sharing a name across source documents become one linked field in the output — flatten them first if they must stay separate. The sources' own bookmark outlines are not merged; enable Create bookmarks instead to get one outline entry per file.

How many files can I merge at once?

There is no enforced limit. The practical ceiling is your device's memory, since every file and the finished document are held in the tab at once. For very large jobs, merging in two stages is more reliable than one.

What happens if I close the tab mid-merge?

Your file list and its order are saved to your browser's local storage as you work, and the page URL carries a session id. Reopening that exact URL restores the session. The merged output itself is not stored, so download it before you leave.

Merging PDFs is the one PDF operation that should be lossless, and usually isn't. Most online mergers rebuild your document: they render each page, re-encode the result, and hand you back a file where the text has become pixels and a 400 KB report has turned into 6 MB. This tool copies pages instead. Every page object — its text, its embedded fonts, its vector artwork, its images at their original resolution — is transplanted into the output document byte for byte.

That has a practical consequence worth knowing before you start: the merged file is roughly the sum of its inputs. Combining five 2 MB PDFs gives you something close to 10 MB, not 3 MB. If the result needs to be smaller, merge first and then run the output through Compress PDF, which is the tool that actually makes size/quality trade-offs and lets you choose them.

The merge runs inside your browser tab using pdf-lib. Nothing is uploaded, which is why there is no file-size cap and no queue — the only ceiling is how much memory your device will hand a single tab.

How to merge PDF files

Add your PDFs
Drop files onto the page, or use Choose files to pick them. You can add more at any point before merging — the button stays available once the first batch has loaded. Files are read as you add them, so a large document may take a moment to show its page count.
Put them in the right order
Files merge top to bottom in the order shown. Drag a tile to move it, or use the arrows on each tile. The A–Z and Z–A buttons sort by filename, which is the fastest route when your files are already named scan-01, scan-02 and so on.
Choose what goes between them
Insert blank pages adds a separator after each file, or only after files with an odd page count — the second option is what you want when the merged PDF will be printed double-sided and each document should start on a fresh sheet. Create bookmarks adds a PDF outline entry per source file, so the result has a navigable sidebar in any reader.
Merge and download
Name the output if you want something other than the default, then press Merge PDF. The file is assembled locally and offered as a download; nothing is stored afterwards, so save it before closing the tab.

What survives the merge, and what doesn't

Page content is copied rather than re-rendered, so anything that lives on a page comes through untouched. A few things live at the document level instead, and those are worth checking in the output:

Text, fonts and vectors: Preserved exactly. Text stays selectable and searchable, embedded fonts come across with the pages that use them, and line art stays resolution-independent.
Images: Preserved at their original resolution and compression. Nothing is downsampled or re-encoded.
Links and annotations: Comments, highlights and link annotations are attached to pages, so they survive. A link pointing at a page inside its own source document still resolves; one pointing at an external file is untouched either way.
Form fields: Copied, but be careful with duplicates. If two source PDFs both contain a field named "Name", they arrive as one shared field and typing in either shows the same value in both. Flatten the forms before merging if they need to stay independent.
Bookmarks: The source documents' own outlines are not carried over. Enable Create bookmarks to get one entry per source file instead — a flat, reliable index rather than a partial reconstruction of the originals.
Encryption: Not carried over, and not readable either. A password-protected source has to be unlocked first; see below.

Mixed page sizes and orientations

Nothing is resized. If you merge an A4 report with a US Letter invoice and a landscape slide deck, the output contains pages of all three geometries, each at its original dimensions. Every PDF reader handles this correctly, and it is the honest result — scaling pages to a common size would mean re-rendering them and losing the fidelity the whole tool exists to protect.

It does affect printing. Most print drivers will either scale to fit or prompt per page, so if the merged file is headed for a printer and consistency matters more than fidelity, standardise the sources before merging rather than after.

Password-protected files

A PDF with a user password is encrypted at the byte level, so its pages cannot be read — let alone copied — until it is decrypted. Files like these will report an error when you add them rather than merging into a broken output.

The fix is to run the file through Unlock PDF first, with the password, and merge the unlocked copy. Note the distinction: a file that opens without prompting but refuses editing carries only an owner password and its permission flags, and those files merge normally.

Working with large batches

There is no limit on the number of files, but every one of them is held in memory while the merge runs, and so is the output. On a desktop browser, several hundred megabytes of input is routine. On an older phone the tab may be killed long before that.

If you are assembling something very large, merging in stages is more reliable than one pass: combine ten files, download the result, then merge the results. Each stage only ever holds a fraction of the total.

Your working set is also kept in the browser's own storage as you go, and the page URL picks up a session id. Reloading that exact URL — or reopening it after a crash — restores the files and the order you had them in. A fresh visit to the plain tool URL always starts empty.

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