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Guide

How to Merge PDF Files Online

5 min read · June 2026

Need to combine multiple PDFs into one file? Whether it's contracts, reports, invoices, or scanned documents, merging them takes seconds — and you don't need to install any software or hand your files over to anyone.

Why Would You Need to Merge PDFs?

There are plenty of everyday reasons people need to combine PDF files:

Whatever your reason, merging PDFs is easier than most people think — and you don't need to install anything to do it.

The Problem With Most Online PDF Mergers

Most online tools work the same way: you upload your files to their server, they get processed, and a download link comes back. Fast and convenient — but your files have just been sent to a third party.

For random documents that's probably fine. But for contracts, invoices, HR files, or anything with personal information, you're trusting that company to handle your data responsibly — delete it after processing, not store it, not scan it. Most reputable tools do the right thing, but you're still relying on their policies and security practices.

How DocKiit Merges PDFs Differently

DocKiit runs entirely in your browser. When you merge PDFs, everything is processed locally using JavaScript — your files never get sent to a server, never touch any infrastructure, and never leave your device. It's not a policy or a promise — it's just how the technology works. There's no server to breach because there's no server involved.

How to Merge PDFs on DocKiit

Step 1: Open the Merge Tool

Head to DocKiit and select Merge PDFs from the homepage. This is a Pro feature — you'll need a DocKiit Pro account to access it.

Step 2: Upload Your PDFs

Click Choose Files or drag and drop your PDFs onto the page. Add as many files as you need — they load instantly in your browser with no upload wait.

Step 3: Reorder if Needed

Drag the files into the order you want them to appear in the final document.

Step 4: Merge and Download

Hit Merge and your combined PDF downloads straight to your device. No watermarks, no "processing" delay, no sign-up prompts mid-flow.

Merge PDFs privately — no upload needed

DocKiit Pro gives you access to PDF merging, compression, splitting and more — all processed locally in your browser. USD $9.99/mo.

Start Pro →

How to Merge PDFs on Mac

Mac users can merge PDFs for free using the built-in Preview app. Open the first PDF in Preview, then go to View → Thumbnails to show the sidebar. From Finder, drag additional PDF files into the thumbnail sidebar in the order you want them. Then go to File → Export as PDF to save the combined file. It works well for simple merges, though for anything more complex an online tool like DocKiit is faster.

How to Merge PDFs on Windows

Windows doesn't have a built-in PDF merger. Your easiest option is a browser-based tool like DocKiit — free to try, no install needed. If you have Microsoft 365, Word can open and combine PDFs to some extent, but the results can be inconsistent with formatting.

How to Merge PDFs on iPhone or Android

Open your mobile browser, go to DocKiit, and follow the same steps as above. No app download needed — it works on any device with a modern browser.

Frequently Asked Questions

Will merging PDFs affect the quality?

No. DocKiit combines PDF pages directly without re-processing or re-compressing them, so fonts, images, and layout are fully preserved exactly as they were in the originals.

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

DocKiit handles most standard use cases. For very large batches or very large individual files, browser-based processing may be slower — but for everyday merges it's instant.

Is it safe to merge PDFs online?

With DocKiit, yes — your files never leave your browser, so there's nothing to intercept. With other tools, you're trusting a third party with your files. For sensitive documents, that distinction matters.

Can I merge password-protected PDFs?

You'll need to remove the password protection first before merging. Most PDF tools require files to be unlocked before they can be processed.

Can I reorder pages after merging?

You can control the order before merging by dragging files into the right sequence. For page-level reordering within a PDF, use DocKiit's Split tool to separate and recombine specific pages.

Does merging increase the file size?

The merged file will be roughly the combined size of the originals. If the result is too large to share, run it through DocKiit's Compress tool afterwards to reduce the size.