This extension adds iOS support for new web APIs that allow websites and webapps to access local files and folders.
iOS has a built in file system sandbox that File Picker participates in. That means no website can access any data you do not explicitly grant permission to open.
Legacy file access must preload the entire file in memory. Websites that use the new APIs along with File Picker extension can read files in chunks at arbitary offsets, saving memory and improving performance.
As per the API specification, writes are only saved when the file is closed by the website. That means you will not lose data if your connection is lost while a file is opened.
Supported websites can open local folders for reading and writing existing files as well as create new files.