Merge PDF
Drop multiple PDF files and merge them into a single document, in the order you choose.
- Browser-only
- No upload
- No login
- No watermark
- Clear instantly
- Open-source engines
Heads upFiles are merged in the order shown. Drag rows to reorder before merging.
Drop files here
or use the buttons below · .pdf
Your file stays on this device · conversion runs locally in your browser
Deep dive
What is Merge PDF?
Merging PDFs combines two or more PDF files into a single document while preserving the original page order, fonts, and formatting. It is one of the most common PDF operations — useful for stitching together contracts, assembling reports, or archiving a set of receipts as one file.
FormatSwitch's Merge PDF tool runs completely inside your browser. Your PDFs are opened locally with pdf-lib, combined page by page, and re-encoded into a single output file. Nothing is uploaded, so even sensitive documents like tax paperwork, medical records, or signed agreements stay private on your device.
When to use it
- Combine multiple invoices or receipts before sending to accounting.
- Merge signed pages back into an original contract or agreement.
- Assemble scanned pages from a phone into one shareable PDF.
- Bundle chapters, appendices, or reference PDFs into one file for archival.
How to use it safely without uploading
Drop your PDF files onto the upload area, drag them into the order you want, then click Merge. The output is generated locally and downloaded straight from your browser. You can clear the queue at any point to remove the files from memory.
Browser-based vs server-based conversion
Most online converters upload your files to their servers, process them there, and then let you download the result. That means your file exists on someone else's computer, often in logs and backups, sometimes indefinitely. FormatSwitch is different: every conversion runs on your device using WebAssembly and the browser's built-in Canvas and PDF engines. Your file never leaves your computer, so there is nothing to leak, nothing to subpoena, and nothing to trust us on — the code that does the work is running right in your tab.
FAQ
Merge PDF — questions people ask
- Can I merge PDF files without uploading them?
- No. Files are processed entirely in your browser using WebAssembly and the Canvas API. Nothing is uploaded to a server, and no copy is kept once you close or refresh the tab.
- Can I reorder PDFs before merging?
- Yes. Drag files in the queue to rearrange them. The final PDF follows that order exactly.
- Is there a file count or size limit?
- There is no hard file count limit. Individual files are checked against a per-file size cap shown on the page to protect your browser from running out of memory.
- Does the merged PDF have a watermark?
- Never. FormatSwitch adds no watermark, logo, or quality cap to your output — the file you download is only what your browser produced.
- Does FormatSwitch store my PDF files?
- No. Files live only in your browser's memory (JavaScript heap). They disappear when you clear the queue, refresh, or close the tab. There is no server, no database, no log.
- Does it work on mobile?
- Yes. Every tool runs on modern iOS Safari and Android Chrome. Very large files may be slower on mobile because of tighter memory limits.