Is this really private? Do my PDFs get uploaded?

No. The entire merge runs in your browser using a WebAssembly-based PDF library. Your PDFs are loaded into memory on your device, combined, and the result is offered for download. There is no upload step. You can verify this by opening your browser's network tab — you will see no requests fired when you click merge.

What is the file size limit?

There is no server-side limit because there is no server. The practical limit is your browser's available memory — typically a few hundred megabytes on desktop and somewhat less on mobile. Very large files may slow down or, on memory-constrained devices, fail.

Does it work offline?

After the page has loaded once, yes. You can disconnect from the internet and the merger will still work. There are no network requests during the merge itself.

Because we don't pay for servers to do the work — your device does it. The site is static HTML and CSS served from a CDN, with the merge code running entirely in your browser. There are no accounts, ads, or premium tiers. The source is on GitHub under the MIT license.

Can I reorder pages within a single PDF?

Not in this tool. This is a merger — it combines whole PDFs in the order you arrange them. A separate splitter tool for pulling specific pages out of a PDF is on the roadmap.

Does this support password-protected PDFs?

Not yet. Encrypted PDFs need the password to be unlocked first. You can unlock them in your PDF reader and re-save without a password, then merge.

tools / pdf-merger

Merge PDF files in your browser.

Drop your PDFs below, drag them into the order you want, then merge. The whole thing runs on your device — your files are never uploaded anywhere.

Drop PDFs here

● Stays on your device. Nothing is uploaded.

How it works

01 Add your PDFs. Drag and drop into the box above, or click Choose files. Multiple files at once is fine.
02 Put them in order. Drag rows to reorder, or use the ↑ and ↓ buttons. Top of the list becomes the first pages of the merged PDF.
03 Merge & download. The merge runs in a background thread in your browser. When it’s done, the combined PDF is offered for download.

How PDF merging actually works

A PDF is a structured file format. Inside, it has a list of objects (pages, fonts, images, metadata) and a cross-reference table that points to where each one lives in the file. Merging two PDFs isn’t just gluing the bytes together — that would break the cross-reference table. A real merger has to copy the page objects from each source PDF into a new document, rewrite the references so they point to the right places, and emit a fresh cross-reference table.

This tool uses pdf-lib, an MIT-licensed PDF library that runs in JavaScript. The merge happens in a Web Worker — a separate background thread — so the page stays responsive even when merging large files.

Because the work happens on your machine, two things follow: your PDFs are never sent to a server, and you don’t need an account or internet connection once the page has loaded.

How this compares

	convert.dcln.me	Typical online merger
Where it runs	● In your browser	Server
Files uploaded	● Never	Yes (stored for hours)
Account needed	● No	Often for >N files/day
Ads	● None	Usually
Works offline	● Yes (after load)	No
Open source	● MIT, on GitHub	No

FAQ

Is this really private? Do my PDFs get uploaded?: No. The entire merge runs in your browser using a WebAssembly-based PDF library. Your PDFs are loaded into memory on your device, combined, and the result is offered for download. There is no upload step. You can verify this by opening your browser's network tab — you will see no requests fired when you click merge.
What is the file size limit?: There is no server-side limit because there is no server. The practical limit is your browser's available memory — typically a few hundred megabytes on desktop and somewhat less on mobile. Very large files may slow down or, on memory-constrained devices, fail.
Does it work offline?: After the page has loaded once, yes. You can disconnect from the internet and the merger will still work. There are no network requests during the merge itself.
Why is it free?: Because we don't pay for servers to do the work — your device does it. The site is static HTML and CSS served from a CDN, with the merge code running entirely in your browser. There are no accounts, ads, or premium tiers. The source is on GitHub under the MIT license.
Can I reorder pages within a single PDF?: Not in this tool. This is a merger — it combines whole PDFs in the order you arrange them. A separate splitter tool for pulling specific pages out of a PDF is on the roadmap.
Does this support password-protected PDFs?: Not yet. Encrypted PDFs need the password to be unlocked first. You can unlock them in your PDF reader and re-save without a password, then merge.