The FileReader web API enables you to make local files available to content running in the browser. This entails a file picker and, depending on the verbiage in

The FileReader web API enables you to make local files available to content running in the browser. This entails a file picker and, depending on the verbiage in your browser UI, that may talk about "upload." That doesn't mean anything is being sent anywhere. See MDN: https://developer.mozilla.org/en-US/docs/Web/API/FileReader https://developer.mozilla.org/en-US/docs/Web/API/FileReader (Or that nothing is; I have not audited this code. But I vouched the parent comment to point out that browsers do offer this capability, and there's nothing facially suspicious in claiming to use it.)