whatStrap writes your Fast Flags and copies your mods in before Roblox starts, then reads the log so you can see which server you landed in. If Roblox isn't on the machine, it fetches that too.
whatStrap✕
whatStrapWhat it does
read from the Roblox log
whatStrap tails Roblox's own log, so it knows the experience you're in and the machine you're on. Rejoin puts you back in the same server. It picks this up whether whatStrap launched the game or something else did.
flags without the flag names
Anti-aliasing, texture quality and display scaling as plain dropdowns and switches. They write the same flags underneath, so anything you set shows up on the Fast Flags page.
%LOCALAPPDATA%\whatStrap\Mods
Mirror Roblox's folder layout and drop your files in. Anything you overwrite is backed up first, so Restore originals puts the install back exactly as Roblox left it.
ClientAppSettings.json
Copy a block of flags from anywhere and press Paste JSON. Booleans get a checkbox so you can flip them without retyping. They're written into the version folder on every launch.
from setup.rbxcdn.com
On a machine with nothing on it, whatStrap pulls the current client straight from Roblox's servers, unpacks it, and installs WebView2 if Windows is missing it. It keeps its own copy current and deletes the old one.
One file. No archive to unpack, no runtime to install first.
You'll see Windows protected your PC, because the file isn't code signed. Choose More info then Run anyway. Every unsigned app gets this screen.
It copies itself into your app data folder and adds Desktop and Start menu shortcuts. The file you downloaded can go in the bin afterwards.