How it works
- You paste a link or type text. It stays in this tab — nothing is sent to a server, which for a QR code matters more than it first appears, since the destination is often an internal or unlisted URL.
- The encoder picks the smallest QR version that will hold your content at medium error correction, then lays out the finder patterns, alignment patterns and timing patterns before writing the encoded data around them.
- Medium error correction means roughly fifteen percent of the code can be damaged or obscured and it will still scan. That is the usual choice for print — high correction survives more damage but produces a denser code that needs to be printed larger.
- The matrix is drawn to a canvas at 512 by 512 pixels with a quiet zone around it, and exported as PNG. The quiet zone is not decoration; scanners need that margin to find the code's edges.
- The PNG is a blob URL held only by this tab. Nothing about the link is recorded, because there is nothing here to record it with.
Limitations
The code is static and cannot be edited or tracked after you download it. The URL is encoded into the pattern itself, so changing where it points means generating a new code and replacing every copy you have printed. If the destination might move, point the code at a URL you control that redirects, and change the redirect instead.
A version 40 code holds about 2,900 characters at this error-correction level, and long content produces a dense code that needs to be printed large and scanned close. Anything past a few hundred characters is usually better handled by putting a short URL in the code and the content behind it.
There is no tracking, no scan count and no analytics, and this is a deliberate limitation rather than a missing feature. Services that offer those work by pointing the code at their own domain and redirecting, which means they can also change or disable your code later. A static code cannot be taken away from you.
Print size and contrast decide whether it scans. A code smaller than about two centimetres on a side, printed on a curved surface, or inverted to light-on-dark, will fail for a meaningful share of scanners regardless of how correct the pattern is. Test it with two different phones before you print a thousand.
Questions
Is my text uploaded?
No. The link stays in the field and the code is generated in this tab. Nothing is posted or logged — worth knowing, because a QR code's contents often reveal an internal URL you would not want in a third party's logs.
What are the limits?
About 2,900 characters at medium error correction, which is the largest QR version. Long content produces a dense code that has to be printed large. In practice, keep it to a URL.
Can I change where the code points after printing it?
Not for this code — the destination is encoded in the pattern. The standard workaround is to encode a URL you control that redirects to the real destination, so you can change the redirect without reprinting.
Does it expire or stop working?
No. There is no service behind it. The PNG you download is the whole code, and it will scan in ten years exactly as it does today, which is not true of codes generated by services that route through their own domain.
Why won't my printed code scan?
Usually size, contrast or the missing quiet zone. Print it at least two centimetres square, keep it dark on light, and do not crop the white margin — scanners use that margin to locate the code's edges.
When people use it
The common case is bridging paper and screen: a menu, a poster, an event badge, a wifi password on a card by the door. The person scanning it has a phone in their hand and no patience for typing a URL, and the code removes a transcription step that fails often enough to matter.
The second case is internal and short-lived — a link to a shared document on a whiteboard, a form for a room full of people, a build to install on a test device. These are exactly the links that should not pass through a third-party redirect service, and a static code generated in the tab is both faster and safer for them.
A 512-pixel PNG is heavier than a web page needs — Compress image brings it down before it goes into an email footer or a page header.
How it compares
The commercial generators offer editable destinations and scan analytics, and those are genuinely useful for a campaign. The cost is that your code depends on their service continuing to exist and continuing to point where you asked — a static code has no such dependency and no expiry. For anything printed at volume with a destination that may change, a redirect you control gives you the same flexibility without handing over the code itself.