How It Works

File Selection

When you select or drag a PDF into the tool, the browser reads the file into memory using the File API. The file bytes are transferred to a JavaScript ArrayBuffer. No network request is made. The file never leaves your device.

WebAssembly Processing

pdf-lib and PDF.js are compiled WebAssembly modules running inside your browser tab. These are the same libraries used in production software — not simplified versions. Compression, page splitting, merging, and password operations all execute here, in local memory.

Output Generation

The processed PDF is written to a new ArrayBuffer, converted to a Blob, and a temporary object URL is created. This URL is used to trigger the browser native download. The Blob is revoked from memory immediately after download initiates.

Memory Cleanup

When you close the tab or navigate away, all file data is garbage-collected by the browser. There is no localStorage write, no IndexedDB entry, no service worker cache for file data. The session is stateless by design.

PDF Engine

pdf-lib 1.17 + PDF.js 4.x

Runtime

WebAssembly (WASM) in-browser

Server Calls

None for file processing

File Transmission

Zero — local only

Framework

Next.js 15 + TypeScript

Hosting

Vercel Edge Network

Max File Size

Device memory limited

Supported Formats

PDF 1.0 — 2.0