PDF Merger
Combine multiple PDF files into one in your browser. Reorder before merging, no upload, no file size limit imposed by a server, no watermark.
Last reviewed by the Radiatus Cloud team
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Merging happens on your device
This tool combines PDFs using the browser's own capabilities, so the files are read from your disk and never transmitted. That matters more for PDFs than for most formats, because the documents people merge are contracts, invoices, medical records, tax returns and scanned identity documents. Every online merger that uploads your files puts copies on someone else's server, usually with a retention window measured in hours, and their privacy policy is the only thing governing what happens in between.
Order is decided before you merge, not after
Pages are concatenated in the order the files are listed, so arrange them first. Reordering afterwards means splitting the merged document apart again. If your files are named with a numeric prefix, sorting by name usually gives the right sequence, but watch for the classic trap where file10 sorts before file2 because the comparison is alphabetical rather than numeric.
What merging preserves and what it drops
Page content, embedded fonts and images carry over intact. Interactive elements often do not survive cleanly: form fields from two documents can collide if they share field names, and digital signatures are invalidated by definition, because a signature attests to a specific byte sequence that merging changes. If a document is signed and the signature must remain valid, it cannot be merged.
Bookmarks and internal links may or may not be preserved depending on how the source files were produced. Links pointing to page numbers within their own document will follow the page to its new position; links pointing at absolute page indices will not.
File size after merging
The result is roughly the sum of the inputs, sometimes slightly less where identical embedded fonts are shared. Merging does not compress. If the combined file is too large for an email attachment, compress it separately afterwards rather than expecting the merge to help.
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Frequently Asked Questions
Are my PDF files uploaded to a server?
No. Files are read and combined in your browser and never transmitted. This matters because merged documents are typically contracts, invoices, medical records or scanned identity documents.
Is there a file size or page limit?
No server-imposed limit, since nothing is uploaded. The practical ceiling is your device's available memory, so very large scanned documents of several hundred megabytes may be slow on a phone.
Will merging break a digital signature?
Yes, necessarily. A digital signature attests to an exact byte sequence, and merging changes it. If a signature must remain valid, the document cannot be merged. Sign after merging instead.
In what order are the pages combined?
In the order the files are listed, so arrange them before merging. Note that alphabetical sorting places file10 before file2, which is the most common cause of an unexpected page order.
Does merging reduce file size?
No. The result is approximately the sum of the inputs, occasionally a little less where identical fonts are shared. Compress the merged file separately if it needs to fit an attachment limit.
Privacy & Security
Runs entirely in your browser. PDF files are never uploaded.
How to Use
Select two or more PDF files in the order you want, then click Merge PDFs to generate one combined file.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
Related Tools
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UtilityParse a User-Agent string into browser, engine, operating system and device. Explains why UA strings are unreliable and what to use instead.
QR Code Generator
UtilityGenerate QR codes for URLs, text, Wi-Fi and contact details. Adjustable error correction and size, produced entirely in your browser.
Credit Card Validator
UtilityValidate a card number with the Luhn algorithm and identify the issuing network from its prefix. Runs locally, nothing is transmitted.