Updates as you type
Your code will appear here.
Quiet zone is the plain margin around the pattern. The spec asks for four modules and real scanners genuinely fail without it, so drop below four only when whatever you're placing the code on already provides the clearance.
Error correction trades capacity for damage tolerance - L recovers roughly 7% of a damaged code, M 15%, Q 25%, H 30%. Whatever you pick, the encoder silently upgrades to the strongest level that still fits the same code size; an arrow on the badge means you got that for free. Reach for H only when the code will be printed small, sit on a curved surface, or have a logo punched into it - on a screen the extra density often costs more than it buys.
No storage, no cookies, no requests. The encoder is a few hundred lines in this file - whatever you type never leaves the tab.