What should it point to
Higher error correction survives more damage — a printed code that might get scuffed, or one with a logo over the middle — at the cost of a denser pattern. The quiet zone is the blank margin scanners need to find the code at all; below 4 modules some readers fail.
Or read a code you already have
Drop in a photo or screenshot of a QR code and the text comes back. It also reads Data Matrix, PDF417 and ordinary barcodes.
Nothing leaves this device. Open your browser's Network tab and watch — your file never appears.
What it says
Most QR generators put themselves in the middle of your link
A large share of the QR tools online do not encode the address you typed. They encode a redirect through their own domain, so that every scan passes through their server and can be counted. That is sold as a feature — analytics, editable destinations — and for some people it genuinely is one. But it has three consequences worth knowing before you print something.
Your code stops working the day that company stops paying for the domain. Every person who scans it is logged by a third party you never chose. And the destination can be changed later by whoever controls the account, which is a real problem for a code on a physical object you no longer possess.
This page encodes exactly the characters in the box. There is no redirect, no account, and no way for us to count anything, because the code is drawn by your browser and we never see it. Scan the result with your phone and the address that appears will be the one you typed.
What error correction actually buys you
QR codes carry redundant data so that a damaged code still scans. The four levels recover roughly 7%, 15%, 25% and 30% of the symbol. Higher levels mean more modules in the same space, so each module is physically smaller when printed — which can make a dense code harder to scan at distance even though it is more robust to damage.
M is the sensible default for a screen or a clean print. Use Q or H if the code will be on something that gets handled, printed small, or partly covered by a logo. Use L only when the content is long and you need the pattern as coarse as possible.
Why the quiet zone matters
The blank margin around a QR code is part of the specification, not decoration. Scanners use it to find the symbol's edges. Four modules is the published minimum, and codes pasted onto busy backgrounds with a thin margin are the most common reason a code that looks fine refuses to scan.
If you are placing the code on a coloured background, keep the quiet zone the same colour as the light modules rather than the background.
What this reads, and what it cannot
The reader handles QR, Data Matrix, PDF417, Aztec, Code 128, Code 39, EAN and UPC. It works on screenshots reliably and on photographs usually — a photo taken at a steep angle, badly lit, or blurred may fail where a phone camera pointed at the same code would succeed, because a phone gets to try many frames a second and this gets one still image.
If a photo will not read, crop it closer to the code and try again. That fixes most failures.
All 39 HermitFile tools
Every one of them runs in your browser. Nothing you open is uploaded, and nothing is stored.