A Web Worker is a small piece of JavaScript that the browser runs in its own isolated thread, separate from the page you see. Blindfold uses Web Workers to do every heavy operation — parsing your file, reading its hidden metadata, and rebuilding a clean copy — inside your own browser. Nothing about your file ever touches a network connection.
Most online privacy tools take a different approach: you upload your file to their server, they run their code there, and they send back a "clean" version. Even when those services promise to delete your file afterwards, you have to trust that promise. Client-side processing removes that trust requirement entirely. Open your browser's DevTools, watch the Network tab while you use Blindfold, and you will see zero file uploads — you can verify the privacy promise yourself in seconds.
This is the same class of technology Figma uses to keep design files responsive and Google Docs uses for spell-check and offline editing: real work, done locally, without round-trips to a server. When you use Blindfold to remove EXIF data from images or strip document metadata from a PDF, the operation runs entirely on your machine — Blindfold is a privacy metadata cleaner that never sees what it is cleaning.
The result is a faster experience and a stronger privacy guarantee. You can clean file metadata online without "online" ever meaning "uploaded." The cleaned file is built in your browser's memory and saved directly to your device. Close the tab and every trace is gone.