Quick Answer: Most web apps send your data to a remote server for processing, creating massive privacy risks. "Local-First" architecture downloads the application logic to your browser and does the processing on your own device. Your data never leaves your computer.
The Problem with The Cloud
When you type a list of student names or corporate employees into a typical team-generator website and click "Submit," that list is transmitted over the internet to a remote server. The server processes it, and sends the answer back. Do they save the list? Do they sell those names? Was the connection encrypted? You have to blindly trust them.
The Local-First Paradigm
Web browsers (Chrome, Safari, Edge) are now incredibly powerful. There is no need for a server to shuffle a list or roll a die. In a Local-First application (like PickRandom.online), all the Javascript code is sent to your browser upfront. When you paste your list of sensitive data and click generate, the calculation happens entirely on your own CPU.
Privacy by Physics
With Local-First tools, you don't need a Privacy Policy drafted by lawyers promising not to steal your data. Your data is protected by the physical limitations of the software architecture. Because no server connection is ever made to transmit the input, data theft is technologically impossible.