How LovelyPDF Works

LovelyPDF processes your PDF files entirely inside your browser. Nothing is uploaded to any server. Here's exactly what happens when you use any tool.

Step-by-step: what actually happens

You select or drop a PDF file

The browser's File API reads your file into memory. The file data stays inside your browser tab — it does not travel over the network.

JavaScript libraries parse the file

pdf-lib or PDF.js (both open-source) parse the PDF binary data inside a browser Worker thread. Your CPU does the work — not a remote server.

The operation runs locally

Merging, splitting, compressing, converting — all of it runs in your browser. For compression, each page is rendered to a Canvas element and re-encoded as JPEG. For merging, pdf-lib combines PDF documents in memory.

Output file is generated in memory

The processed PDF is assembled as a Blob (binary data) in your browser's memory — a temporary object URL is created pointing to it.

You download the file

Clicking download triggers a standard browser file download. The file saves directly to your device from memory.

Memory is cleared

After a 45-second countdown, the object URL is revoked and the data is released from memory. No trace of your file remains.

The technology stack

pdf-lib

An open-source JavaScript library for creating and modifying PDF files. Used for merge, split, rotate, watermark, metadata editing, header/footer, page management, and form filling. Runs entirely in the browser.

PDF.js (Mozilla)

Mozilla's open-source PDF renderer for the browser. Used for rendering pages as canvas elements (compress, grayscale, rotate preview), and reading form field positions for the live form filler.

JSZip

Used for tools that output multiple files (like PDF to image). Packages all output images into a single .zip file in the browser.

docx.js

Used by the PDF to Word tool to assemble a .docx file from extracted text, entirely in the browser.

How to verify it yourself

The Network Tab test

1. Open LovelyPDF in Chrome or Firefox

2. Press F12 to open DevTools → click the Network tab

3. Use any tool — drop a PDF, process it, download the result

4. Check the Network tab — you will see zero file upload requests

5. The only requests visible are loading JS libraries from CDN — no file data

What this means for your privacy

Your files cannot be intercepted in transit because they never travel over the network
No company, government, or hacker can access your documents through LovelyPDF
Safe for sensitive documents: contracts, medical records, financial statements, identity documents
No data retention policy needed — there is no data to retain
Works in airplane mode (after the initial page load)

Are there any limitations?

File size: Limited only by your device's available RAM. Modern devices handle files up to several hundred MB easily. No artificial limit is imposed by LovelyPDF.
Password-protected PDFs: pdf-lib cannot decrypt encrypted PDFs. If your PDF requires a password to open, it cannot be processed.
Scanned PDFs: A scanned PDF is a PDF containing images, not text. PDF to Word extraction will not return useful text. All other tools work normally.
Browser compatibility: Works in all modern browsers — Chrome, Firefox, Safari, Edge. Internet Explorer is not supported.

See it for yourself — use any tool free, right now.

Open LovelyPDF →