1Upload every file you want combined — at least two of them.
2Add the files in the order you want them joined; the first file you add comes first.
3Start the merge; the files are joined one after another into a single file.
4Download the single combined PDF file.
Merge PDF FAQ
Is the merge lossless?
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It is whenever the inputs already agree — the encoded data is copied straight through. It stops being lossless only when the inputs disagree and something has to be re-encoded to make them compatible, and even then it is one pass, not one per file.
How does Merge PDF join the files together?
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Concretely, the page trees are appended into one document, so text stays selectable, bookmarks are merged into a single outline and nothing is rasterised anywhere in the process. Upload everything you want combined and the result comes back as a single file.
Anything specific to PDF when merging?
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Yes — a PDF is an object graph, not a page image, so text stays selectable and vectors stay sharp no matter what happens to the raster content inside it. That is worth checking when the inputs did not all come from the same source.
What can I upload to Merge PDF?
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Any standard PDF, including ones produced by a scanner, by a word processor or by a print driver. Files with an owner password that only restricts editing are handled; files that need a user password to open are not, and we do not attempt to break encryption.
Is there a file size limit on Merge PDF?
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Yes: free use has a size limit per document, and the page tells you when a file is over it; Ghostscript and qpdf do the work. Scanned PDFs are the usual thing that exceeds it, and compressing the document first is normally enough to bring it back under.
Will Merge PDF lower the quality of my PDF documents?
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Text and vector artwork are objects rather than pixels, so they stay perfectly sharp at any zoom no matter what happens. Only the embedded raster images can degrade, and only if the operation you chose resamples them.
Can I run Merge PDF on several PDF documents at once?
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Yes — upload the set and they process in parallel under one set of settings, which is the point of doing a document workflow here rather than clicking through a desktop reader.
Why does a EPUB site host Merge PDF?
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EPUB.to is built around the open eBook format — XHTML in a zip, reflowable by design, and readable on hardware nobody has thought about the layout for. A book is a zip full of markup, images and fonts, so almost every job people bring to an eBook site is really a job on one of those things. Merge PDF runs on the same upload and the same account as the conversions because that is where it is needed.
What should I do with the result once Merge PDF is finished?
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The converter on this site moves books between EPUB, MOBI, AZW3, PDF and DOCX, so a title ends up on whatever hardware is actually going to read it. Doing that after Merge PDF means the conversion is made from the version you settled on, not from the one you were still fixing.
Is Merge PDF here the same tool the sibling sites run?
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The engines are shared — the same toolchain, the same workers, the same limits. What a EPUB site adds is a view on reflow: which of these operations a reflowable book genuinely supports, and which ones only make sense on the fixed-layout media inside it. It also starts from one fact about the format this site is named after: the book is a zip of XHTML with a manifest, so the text costs almost nothing and every decision that matters is about the embedded images and font subsets.
Do I need an account, and does anything get kept?
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No account is needed. Uploads and results are kept for about 24 hours, which leaves time to download the result, and are then deleted automatically; nobody reads, lists or indexes them. Several files in one job need a paid plan.
