What is the per-file size limit?

There is no hard limit set in the code. In practice a single 100MB PDF will load fine on a laptop; 500MB might exhaust memory on a phone. If you have one giant PDF, run it through the compress tool first or split it before merging — both options are in the related-tools list. The page reports an error cleanly when memory runs out, so you do not lose the rest of your batch when one file is too big.

Will the output keep my original metadata?

The output inherits title, author, and creation date from the first file in the merge order. The other files' metadata is discarded — there is no PDF-standard way to merge metadata fields like "all authors of all input files". If you need a specific title or author on the output, edit the first file's metadata in Acrobat or LibreOffice before merging, or use a separate metadata editor on the final merged PDF.

There is no undo button — once you download the merged PDF and remove the source files from the page, the originals are still on your disk unchanged because the page never modified them. The merge writes a new file. If you want to undo, just go back to your original files. If you mean "can I split the merged PDF back into pieces", yes, the PDF split tool does that, and the related-tools list at the bottom of the page links to it.

Does it work offline?

Yes, after the page has loaded once. The pdf-lib WebAssembly module is small enough that browsers cache it, and the whole tool runs client-side, so subsequent visits work without an internet connection. The first load needs to fetch the JS bundle, but after that you can merge PDFs on a plane or in a basement with no signal.

Are interactive form fields preserved?

Partial yes. Field widgets on each page carry through visually and remain fillable in the merged output, but if two source PDFs have form fields with the same name there can be value-sharing collisions (filling one fills the other in the merged doc). For clean form merging, rename fields in Acrobat before merging, or merge first and then flatten the form in the output PDF.

Can I merge PDFs of different page sizes?

Yes. Each page keeps its original dimensions in the merged output. So you can mix A4 and Letter pages, portrait and landscape, even custom-size pages from a brochure or poster, and they all coexist in one PDF. PDF readers will display each page at its own size, which is what you want when the source documents had different formats. There is no automatic resizing or letterboxing.

Why does my merged file have a generic title like "Untitled"?

Because the first file in the merge order had no title metadata set, or had a generic title from whatever tool created it. The output PDF inherits its title, author, and creation date from the first file in the merge sequence. To set a specific title, edit the first input file's metadata in Acrobat, Preview, or another PDF editor before merging — or edit the merged output's metadata afterward.

Can I reuse the page after closing the browser tab?

Yes. The page caches in your browser like any other site, so reopening it loads from cache instantly. Your previous merge state is gone (no server-side history is kept, since nothing was ever sent to a server), but the tool itself loads in a second on second visits. For frequent use, bookmark the page or pin it as a Chrome app for one-click access.

Merge PDF Files Online Free

Combine PDFs in the order you want them, in your browser, with no upload and no watermark.

In your browser—your files never leave your device.

Learn more

Files never leave your browser. Merging happens 100% locally on your device.

PDF merging sounds like a five-second task and most of the time it is, but the free tools out there make you sign in, queue you behind a paywall, or slap a banner on the first page of your output. This one does not. Drop two or more PDFs in, drag the tiles around until the order matches what you want, and download a single combined file. Everything runs in your browser using a WebAssembly build of pdf-lib (the @cantoo fork, actively maintained), so the files never leave your device. Once you have the order you like, the merge itself takes a few seconds even for ten or twenty files. The output has no watermark, no banner page, no cover sheet. Metadata, hyperlinks, and bookmarks from the original files carry through. The steps below cover the whole flow, and the FAQ at the bottom answers the questions that come up after the first successful merge.

How to merge pdf files online free

Drop in your PDFs

Drag two or more files onto the upload area, or click to browse. The page accepts any standard PDF, including ones produced by phone scanner apps.
Drag to reorder

The output follows whatever order is on screen. Grab a tile by its handle and move it up or down — no "move up" buttons, no separate ordering screen.
Click Merge PDFs

The page copies each file into a single new document. Ten PDFs takes about three to five seconds on a modern laptop, longer on a phone.
Download the result

A download link appears named after your first file (e.g. cv-merged.pdf). You can keep adding files and re-merging without refreshing the page.

Features

Drag-to-reorder before merging

Each uploaded file shows up as a card you can drag into the position you want. The output follows screen order, so what you see is what you get. No popup dialogs, no separate ordering step, no clicking arrows one row at a time when you have uploaded twenty pages. If you accidentally added the wrong file, there is a remove-X on each card. The whole UI was built around the assumption that getting the order right is the actual work; the merge itself is trivial.

No file count limit (within browser memory)

I have personally merged 50+ PDFs in a single batch without issues on a 16GB MacBook. The only real ceiling is your device's RAM — a Chromebook with 4GB will choke earlier than a desktop. If the browser runs out of memory the page shows the error instead of silently failing or freezing, so you know to split the batch. Most consumer-tier tools impose a hard 5-file cap to push you onto a paid plan; this page does not because there is no plan.

Bookmarks and hyperlinks survive

Internal bookmarks from the first file carry over into the merged output. Hyperlinks (both external URLs and intra-document cross-references) stay clickable. Page orientation is preserved per page, so mixing portrait and landscape source files works correctly — each page keeps its original dimensions and rotation. Form fields on a per-page basis also carry through, which matters when you are stapling a signature page onto a longer contract.

Clean output with no inserted content

No watermark, no banner page, no cover sheet, no QR code stamped into a corner, no "converted by" footer. The output is exactly the concatenation of your inputs. Metadata (title, author, creation date) is inherited from the first file in the list, which is usually what you want for a cover-letter-plus-attachments combo or a multi-section contract where the first page is the title page.

Privacy & security

The merge runs on pdf-lib (the @cantoo fork) inside your browser tab — no PDF byte is ever uploaded to our server. We hand the heavy lifting to a Web Worker so the page does not freeze while a long batch processes, but the worker is also in your browser, not a backend. When you download the merged file, that is your browser writing to disk from memory; we never see the resulting PDF and there is nothing for us to delete on a timer because nothing was stored.

Frequently asked questions

Is there a file count limit?

Not a hard one in the code. The page handles two to fifty files comfortably on a modern laptop. Above that you start hitting browser memory limits, especially on lower-spec devices or phones. If you need to merge a hundred scanned pages, split the batch into two passes — merge halves separately, then merge the halves. The progress indicator shows which file is being processed so you can spot a stall before it locks up the tab.

Are my files uploaded anywhere?

No. The merge runs entirely in your browser using a WebAssembly build of pdf-lib. You can verify this in the Network tab of your browser's developer tools while merging — there are no outgoing requests for the file bytes, only the initial static assets that loaded when you opened the page. The output blob is generated locally and the download is served from a temporary in-memory URL that gets revoked when you close the tab.

Will I lose quality after merging?

No. The merge concatenates pages without re-encoding them. Text stays selectable, vector graphics stay sharp, and embedded fonts carry through. The file size of the output is usually the sum of the inputs minus a small overhead from pdf-lib's de-duplication of shared resources. Do not expect compression as a side effect — for that, run the merged output through the PDF compress tool afterward, which is in the related-tools list at the bottom of the page.

What happens if one of my PDFs is password-protected?

The merger refuses to read an encrypted file and tells you which one in an error message. Unlock it first with the PDF unlock tool (you need the password), then come back and merge. Quietly skipping a locked file would be worse — you would think the merge worked and only find out later that one section is missing. The two-step flow is annoying but it prevents subtle data loss, which I think is the right trade-off.

Does it work on a phone?

Yes. Any modern mobile browser handles the merge — tested on iOS Safari and Chrome on Android. The bottleneck is memory rather than CPU, so a phone with 4GB of RAM can comfortably merge five or ten regular PDFs. For 50+ files I would still reach for a laptop. The drag-to-reorder UI uses touch handles that work with a finger; you do not need a stylus or a mouse.

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