Client-Side Processing
Standard PDF tools execute entirely within your browser's local memory via WebAssembly and JavaScript. Your documents are not uploaded to PDFHub servers.
Privacy Center
PDFHub is built around a simple principle: your documents belong to you. Understand how our browser-based tools process files, when external services are contacted, and how your local preferences are managed.
Zero Server Storage
We maintain no file storage infrastructure, no user database, and no document logging servers. Files disappear from memory when you close your tab.
No Accounts or Tracking
No user accounts, passwords, or emails required to use any tool. We do not set tracking cookies or embed advertising telemetry pixels.
Declared Network Needs
Where a feature relies on an external service (such as translation or OCR language downloads), that network activity is disclosed explicitly below.
Architecture
How PDFHub processes files locally in your browser
Traditional online PDF websites require uploading your documents to remote cloud servers, transforming them in a datacenter, and sending a download link back. PDFHub takes a fundamentally different, privacy-first approach:
1
Local File Reading via HTML5 File API
When you drag or select a PDF, your browser reads its binary data into temporary local memory (ArrayBuffer) directly on your device.
2
In-Memory Transformations via Client-Side Engines
Our tools utilize audited client-side engines such as pdf-lib, PDF.js, HTML5 Canvas, and docx/xlsx libraries executing entirely within your browser sandbox.
3
Local Blob Export Directly to Your Storage
The resulting modified PDF is packaged into a local binary object URL (blob:) and saved to your device's downloads folder. The file never leaves your computer.
Transparency Matrix
Tool-by-Tool processing breakdown
Not all PDF operations are identical. Below is an honest, verified audit of how each category of tools operates in PDFHub:
| Tool Category | Processing Engine | Network Transmission | Server Storage |
|---|---|---|---|
| Standard PDF Operations Merge, Split, Compress, Edit, Sign, Rotate, Crop, Page Numbers, Watermark, Protect, Unlock, Repair, Remove/Extract Pages, Convert (Word/Excel/PPT/Images/Markdown) | 100% Client-Side (pdf-lib, PDF.js, Canvas) | None (0 bytes uploaded) | Zero (Never uploaded to any server) |
| OCR PDF Optical character recognition and text extraction from scanned documents | Client-Side Worker (Tesseract.js) | One-time download of public OCR trained language models from CDN into memory. Image recognition executes locally on your machine. | Zero (Document pixels never leave browser) |
| Translate PDF Translating extracted document text into foreign languages | External API (MyMemory API) | Extracted text fragments are transmitted to the free public MyMemory Translation API (api.mymemory.translated.net) to retrieve translations. |
Governed by MyMemory API policies. Do not submit confidential text. |
| AI Summarizer Generating key bullet points and summaries of lengthy documents | Hybrid / Local | If configured with an external AI endpoint, prompts are transmitted to that provider. If no endpoint is configured or if requests fail, it falls back to a 100% local word-frequency algorithm. | Local fallback has zero server storage; API mode governed by chosen provider. |
| Scan to PDF Capturing document photos directly from your web camera | 100% Client-Side (WebRTC / Canvas) | Camera stream is rendered locally onto HTML5 Canvas without network transmission. | Zero (Photos remain in browser memory) |
External Resources
Third-party CDNs and network dependencies
PDFHub is delivered as a static web application hosted on Cloudflare Workers and Netlify. To deliver fast global performance and dependable typography, the site loads the following static third-party resources:
Cloudflare cdnjs (cdnjs.cloudflare.com)
Delivers static JavaScript libraries (pdf-lib, pdf.js, font-awesome, docx, xlsx, pptxgenjs, tesseract.js). Subject to Cloudflare's privacy policy. No document contents are sent to cdnjs.
Google Fonts (fonts.googleapis.com)
Delivers web fonts (Syne, DM Sans). Subject to Google Fonts' privacy policy. Google receives standard browser HTTP request metadata (IP address, user-agent) to serve font stylesheets.
MyMemory Translated API (api.mymemory.translated.net)
Used exclusively by the Translate PDF tool when a translation request is initiated by the user. Only the text chunks to be translated are sent.
Tesseract CDN (unpkg.com)
Used by the OCR tool to download pre-trained language model data files (e.g. eng.traineddata). Document content is not sent to unpkg.
Local Storage
Application data stored in your browser
PDFHub uses HTML5 localStorage exclusively to save your interface preferences. It does not use tracking cookies, analytics identifiers, or cross-site tokens. Here is the complete inventory of keys stored:
pdfhub-theme
String ('dark' | 'light')
Preserves your chosen color theme so your preference is retained when navigating between pages or revisiting the site.
pdfhub-favorites
JSON Array
Stores the list of tool URLs that you have starred on the homepage for fast one-click access.
pdfhub-history-tools
JSON Array (max 12 items)
Stores the names and URLs of the last tools you opened so you can quickly return to recent utilities from the menu or dashboard.
pdfhub-notifications-seen
String ('true' | 'false')
Records whether you have viewed local update announcements in the dashboard to prevent showing repeated notices.
Interactive Control
Manage Local PDFHub Data
View and manage the local records stored in this browser for PDFHub. This data remains on this device and can be reset at any time.
Theme Preference
Dark
Active UI color mode
Saved Favorites
0 tools
Pinned home shortcuts
Tool History
0 tools
Recently accessed tools
Update Status
Default
Notification state
What will be cleared:
- Your theme preference (resets to default Dark theme)
- All pinned favorite tool shortcuts
- Your recent tool access history
- Local notification viewing records
What will remain untouched:
- Any PDF files already saved to your downloads folder
- Browser bookmarks, history, and cache of other websites
- Your browser's security settings and extensions
Data resides in this browser's localStorage.
Security & Best Practices
Security limitations & user responsibilities
While client-side processing eliminates interception risks over transit to an application server, browser-based tools carry specific considerations:
Public & Shared Computers
If you process private documents on a shared library, school, or workplace computer, subsequent users could potentially view recent tool URLs in browser history or recover files left in the browser's download folder. Always use the Clear Local PDFHub Data action above and close all browser windows when finished.
Browser Extension Safety
Third-party browser extensions (such as screen recorders, ad blockers, or grammar checkers) have broad permissions to inspect web pages. Avoid running untrusted browser extensions when working with sensitive legal, financial, or personal records.
Keep Original Source Backups
PDF operations like page deletion, splitting, and compression permanently alter document structure. Never rely exclusively on a modified output without retaining an unmodified backup of your original document.
Privacy questions or security disclosures?
If you have questions about how a particular tool works or wish to report a security finding, contact the developer directly.