How PageSwap Works
Understanding our 100% local, privacy-first approach to PDF manipulation
Your Privacy is Our Priority
PageSwap processes everything locally in your browser. Your PDF files are never uploaded to any server. They never leave your device. We don't have servers to store your files - everything happens right on your computer using JavaScript.
Technical Process
File Upload
When you select or drop PDF files, they are read directly into your browser's memory using the FileReader API. The files are converted to an ArrayBuffer - a raw binary representation that stays in your browser's memory.
PDF Rendering
We use PDF.js, Mozilla's open-source PDF rendering library, to parse and display your PDF pages. PDF.js runs entirely in JavaScript and renders each page to an HTML Canvas element for preview. This is the same technology Firefox uses to display PDFs.
Page Reordering
The drag-and-drop functionality is powered by Sortable.js, a lightweight JavaScript library. When you drag pages around, we're simply reordering references in memory - the actual PDF data remains unchanged until export.
PDF Creation
When you export, we use pdf-lib, a powerful JavaScript library that can create and modify PDF documents. It extracts pages from your original PDFs (without re-encoding them) and combines them in your specified order. This preserves the original quality - no compression, no quality loss.
Download
The final PDF is created as a Blob (binary large object) in your browser's memory. We create a temporary download link and trigger the browser's native download function. The file goes directly to your downloads folder - never touching any server.
Data Flow
What We DON'T Do
Your files are never sent to any remote server
We don't track what's in your PDFs or collect any document data
Your files don't go to AWS, Google Cloud, or any cloud service
Pages are copied, not re-encoded - original quality preserved
The only local storage we use is for your theme preference (dark/light mode)
Open Source & Transparent
PageSwap is completely open source. You can inspect every line of code on our GitHub repository. The entire application consists of three files:
index.html- The page structurestyles.css- Visual stylingapp.js- All the PDF processing logic
You can download the entire project and run it locally - it will work exactly the same because there's no server-side component!
View on GitHubFrequently Asked Questions
Is there a file size limit?
Since processing happens in your browser, limits depend on your device's available memory. Modern browsers can typically handle PDFs up to 100-200MB comfortably. Very large files might be slow but will still work.
Does this work offline?
After the initial page load, yes! The JavaScript libraries are cached by your browser. You can even save the page locally and use it completely offline.
What browsers are supported?
PageSwap works on all modern browsers: Chrome, Firefox, Safari, Edge. We recommend using the latest version for best performance.
Can I merge PDFs from different sources?
Absolutely! Upload multiple PDFs and arrange pages from different files in any order you like.
Why is this free?
We believe essential document tools should be accessible to everyone. There are no premium tiers, no "upload limits," no watermarks. If you want to support development, you can buy me a coffee.