Every online PDF merger asks you to upload your files to their server. ModernPDF is the exception. Your PDFs are combined entirely inside your browser — no file ever leaves...
Open Merge PDFCombine confidential documents without sending them to a third-party server.
Files are never transmitted. Verify in your browser's Network tab — no outbound requests during processing.
PDF merging runs via compiled WebAssembly in your browser. Same performance as desktop software, with browser-level isolation.
No server stores your files. No database to hack. No employee access. The data never exists outside your device.
Drag PDFs into the browser. Files are read from your device's file system directly into browser memory.
WebAssembly combines the PDF structures. Page ordering, bookmarks, and metadata are preserved. No server call.
The merged file downloads directly. Close the tab and all data is gone from memory.
Most PDF tools promise to delete your files after processing — typically within 1-2 hours. But by then your document was transmitted, received by a server, written to disk, and processed by unknown software.
During that window, the file exists on infrastructure you don't control. It may be cached by CDN nodes, logged by monitoring systems, or backed up automatically. "We delete it" means "we delete the copy we know about."
ModernPDF eliminates this entirely. No upload, no server copy, no temporary file, no deletion step. The strongest data protection is not having the data at all.
Open Developer Tools (F12), go to the Network tab, then merge your files. Zero outbound data transfers. The only network requests are for static page assets loaded when you first open the tool.
They're gone. Files exist only in browser memory during your session. Closing the tab releases that memory. No persistent storage anywhere.
Zero-upload architecture addresses a key HIPAA concern: protected health information never leaves the covered entity's device. No BAA is needed because no PHI is transmitted to or stored by ModernPDF.
Yes. The tool runs as client-side JavaScript and WebAssembly. Your IT team can inspect source code, monitor network traffic, and verify no file data leaves the device. We also publish a security whitepaper.
WebAssembly uses your device's memory and CPU. Modern browsers handle files up to hundreds of megabytes. Pro users can process files up to 500MB.
Free to start. Files stay on your device. Upgrade to Pro for unlimited use.
Open Merge PDF