How-to Guide 2 min read

How to Merge PDF Files Online Free

Merging PDFs is one of the most common document tasks — combining a cover letter with a resume, assembling a multi-part report, or joining several scanned pages into one file. ImgToolkit's PDF merger combines multiple PDFs into a single document entirely in your browser. No files leave your device, no account needed, no cost.

Files never leave your device ⚡ Instant browser processing 🆓 100% free — no account 🚫 No watermark on output

By ImgToolkit Team · Updated May 2026 · 2 min read · Processed in your browser

PNGJPGWebPGIF

Quick Answer

Try it now — free, no signup

Your images stay on your device. Nothing is uploaded to any server.

Merge PDFs Free

Step-by-Step Guide

4 steps · takes under 1 minute

Open the Merge PDF tool

Navigate to the Merge PDF tool on ImgToolkit.

Upload your PDF files

Drop in all the PDFs you want to merge. Upload them in the order you want them to appear.

Reorder if needed

Drag and drop the uploaded files to change their order before merging.

Merge and download

Click Merge. Your combined PDF downloads immediately — all pages in sequence.

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100% Private — Zero Uploads

ImgToolkit runs entirely in your browser using the Canvas API. Your images are never sent to a server, never stored in the cloud, and never seen by anyone else. This makes it safe for sensitive documents, client work, medical imagery, and confidential screenshots.

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Pro tip

Use 75–85% quality for web images — you get 60–80% smaller files with no visible difference at normal screen sizes.

Format & File Size Comparison

Same 1080×1080px photo processed four ways

Format	Quality	File Size	Notes
PNG (original)	Perfect	4.2 MB	No compression — too large for web
Compressed PNG	Visually identical	1.1 MB	−74% — transparency preserved
JPG (85% quality)	Excellent	310 KB	−93% · Best for photos
WebP (85%)BEST	Excellent	205 KB	−95% · Recommended for web

Based on a 1080×1080px photo. Results vary by image content and complexity.

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Frequently Asked Questions

4 questions answered

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

There is no set limit — the tool handles as many PDFs as your browser can load in memory. For merging very large numbers of PDFs (50+), a desktop app like PDF24 Creator may be more reliable.

Can I merge PDFs with different page sizes?

Yes. The merged PDF preserves each source document's original page size. If your PDFs have different dimensions (A4 and Letter, for example), the merged document will have mixed page sizes — most PDF viewers handle this correctly.

Will merging PDFs reduce quality?

No — merging is a structural operation that combines pages without re-processing the content. Images, fonts, and formatting are preserved exactly as in the source PDFs.

Can I merge password-protected PDFs?

Password-protected PDFs need to be unlocked first. Use the PDF Password Remover tool to remove the password, then merge the unlocked files.

Ready to get started?

Free, instant — your files stay on your device. Always.

Merge PDFs Free

Merge PDF

Free · Browser-based · No account

Merge PDFs Free

Privacy First

Your images are processed entirely in your browser using WebAssembly. No files are ever uploaded to a server.

What's included

Merge unlimited PDFs in one step