Merge PDF Files
Combine multiple PDFs into one — runs entirely in your browser.
Drop PDF files here
Nothing is uploaded — files stay on your device
Every PDF tool on PDFree runs entirely in your browser using WebAssembly. Your files never touch any server. Works offline after your first visit.
Most PDF tools online work the same way: you upload your file to their server, their server processes it, and you download the result. This means your document — potentially containing contracts, medical records, financial data, or personal information — travels across the internet and temporarily lives on someone else's infrastructure.
PDFree is architected differently. The PDF processing engine runs inside your browser using WebAssembly. When you drop a file into PDFree, the browser reads it from your disk directly. No bytes of your document are transmitted anywhere. The output is generated in memory and downloaded straight to your device.
How browser-side processing works: Your PDF is read by the browser's File API (local disk access only). WebAssembly modules (pdf-lib, PDF.js) process the file entirely in memory. The result is written to a Blob URL and downloaded — it never touches a network socket.
Combine multiple PDFs into one file — no size limit, no upload
Extract pages or split into multiple files — locally
Reduce file size 20–80% without quality loss, in your browser
Fix sideways or upside-down pages — embedded permanently
Add CONFIDENTIAL, DRAFT, or any text stamp — no upload
AES-256 password encryption — key never leaves your device
Convert photos and images to PDF — processed locally
Export PDF pages as high-quality images — no upload
Pull specific pages into a new PDF — browser-only
Add page numbers to PDF — Arabic, Roman, or ABC formats
View and edit title, author, keywords — all local
Permanently cover sensitive text and images — offline safe
Type in forms, tick checkboxes, add signature — no upload
Convert PDF to editable .docx — processed in browser
Annotate, highlight, and draw on PDF pages — locally
Add notes, comments, and stamps — no server needed
PDFree uses three technologies to process PDFs without any server:
WebAssembly is a binary instruction format that runs in all modern browsers at near-native speed. PDFree uses Wasm to run PDF manipulation code directly in your browser — the same code that would otherwise run on a server now runs on your machine.
pdf-lib is a JavaScript library for creating and modifying PDF documents. PDFree uses it for operations like merging, splitting, rotating, watermarking, and adding page numbers. All manipulation happens in browser memory.
PDF.js is Mozilla's PDF reader and rendering engine, also built entirely in JavaScript. PDFree uses it for operations that require rendering pages — like converting PDF pages to JPG images. It runs fully client-side.
A service worker caches all the scripts, WebAssembly modules, and fonts on your first visit. On subsequent visits — even with no internet connection — the tools load from cache and process PDFs entirely offline. This is the same technology used by native-app-like Progressive Web Apps (PWAs).
When a tool processes your PDF on a server, several things happen: your file is transmitted over the internet (encrypted, but still), it lands on their infrastructure, it gets written to disk or memory, and their code handles it. Even if a provider deletes files after processing, there is a window of exposure.
PDFree eliminates this entirely. Because no server is involved:
Yes. After your first visit, PDFree works fully offline. A service worker caches the entire application — scripts, WebAssembly modules, and fonts. On any subsequent visit, even with no internet, all tools load from cache and process PDFs without needing a network connection.
No. Your PDF is read from your local disk by the browser's File API and processed in browser memory. No bytes of your file are sent over a network connection. You can verify this yourself by opening your browser's DevTools → Network tab and watching for any file upload requests — there are none.
Cloud-based tools upload your file to their servers, process it remotely, and send the result back. Your document is temporarily on their infrastructure. PDFree is the opposite — the processing engine lives in your browser. Your file never leaves your device. This makes PDFree fundamentally safer for sensitive documents and usable without internet after the first load.
Yes. PDFree works on iOS Safari, Android Chrome, and all modern mobile browsers. The WebAssembly-based processing works the same on mobile — no upload, no server. You can also install PDFree as a PWA from your browser's menu for quick offline access from your home screen.
Yes. PDFree has no paid plan, no daily limits, no file size caps, no watermarks on output, and no account required. All tools are free forever. The project is open source under GNU AGPLv3 — you can inspect the source code to verify exactly how it works.
No signup. No download. Works in your browser right now — and offline after first visit.
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