Browser Processing Policy
A plain-language explanation of how our tools work without uploading your files.
Last updated: June 2026
The short version
When you use one of our tools, your file is opened by your browser, processed by JavaScript running on your own computer or phone, and the result is handed back to you. The file never travels across the internet to us. That's why our tools are fast and private.
The technologies involved
- File API reads your selected file into the page's memory.
- HTML5 Canvas powers image resizing, conversion, cropping and filters.
- pdf-lib & PDF.js read and write PDF documents entirely client-side.
- SheetJS & Mammoth.js parse spreadsheets and Word documents locally.
- Web Crypto API generates hashes and secure random values in the browser.
What does leave your browser
To keep pages light, some tools load their library from a public CDN (a code file), and the site shows advertising. These involve standard web requests for code and ads — never the contents of your file. You can confirm this yourself with your browser's developer tools.
Limits of browser processing
Because the work happens on your device, very large files are bound by your device's available memory, and a few advanced, server-only operations are intentionally out of scope. For the vast majority of everyday tasks, browser processing is faster and safer than the upload-based alternative.