Merge PDF files
Combine multiple PDFs into a single file in any order — privately, in your browser. PDF Lab merges files locally on your device, so nothing is ever uploaded.
or drop files here
Tip: select multiple files with Ctrl/Cmd or drag many at once.
How to use Merge PDF
- 1Click "Select PDF files" and choose two or more PDFs from your device.
- 2Drag the files into the order you want them merged using the ↑ ↓ buttons.
- 3Click Merge PDF. The combined file is created in your browser and downloaded.
Why use PDF Lab
- Combine any number of PDFs into a single file.
- Files stay on your device — nothing is uploaded to any server.
- No account, no signup, no watermark on the output.
- Free to use with no per-file limits beyond your device's memory.
- Works on desktop and mobile browsers, including offline after first load.
- Reorder files freely before merging.
Your file never leaves your browser
Merge PDF runs entirely on your device using pdf-lib and pdf.js — both self-hosted by PDF Lab, so no third-party CDN sees your traffic. There is no upload, no account, no log of your file.
How browser-based PDF processing works →Merge PDF — questions
- No. Every operation runs in your browser using JavaScript. Your file is loaded into your browser's memory, processed, and a result is saved to your device. Nothing is sent over the network.
- No. Because the processing happens in your browser, neither PDF Lab nor any third party has access to the file contents. You can verify this by opening your browser's network tab while using the tools — no file data is transmitted.
- There is no enforced limit, but performance depends on your device's memory. Most modern browsers comfortably handle PDFs up to about 100 MB. Very large files may slow down your browser tab.
Are my files uploaded to your server?+
Can PDF Lab see the contents of my files?+
Are there file size limits?+
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