QR Code Generator

What the QR Code Generator Does

Paste a link, a Wi-Fi string, a phone number or plain text into the box; a QR code appears within a quarter-second and refreshes as you type. Drag the size from 80 to 800 pixels, choose the dark color, and click Download PNG when it looks right. The light squares stay white so scanners keep the contrast they rely on.

Everything is drawn on your own device, so the text you encode is never sent anywhere. Because the code is static, whatever you type is baked into the black-and-white pattern itself: there is no short link hidden in the middle, no redirect, and no dashboard that could later change it or switch it off.

How It Works

The qrcodejs library takes your text, picks the smallest QR version (symbol size) that will hold it, and lays out the dark and light modules — the little squares — according to ISO/IEC 18004. It draws them onto an HTML canvas at the pixel size you set.

The tool keeps the library's default error-correction level, which is H, the highest of the four. Roughly 30% of the code can be smudged, torn or covered and it will still scan — that redundancy is what lets a QR survive being printed on packaging or having a small logo dropped in the centre. Download saves that canvas as a PNG.

Generation algorithm

1. Read the input. Take the text or URL exactly as typed — a link, Wi-Fi credentials, a vCard or any UTF-8 text.
2. Pick the version. qrcodejs chooses the smallest of the 40 QR versions — from 21×21 up to 177×177 modules — that can hold your data at error-correction level H.
3. Encode with Reed–Solomon. The data is encoded and interleaved with error-correction codewords, so a damaged code can still be decoded.
4. Lay out the modules. Finder patterns, timing rows and your data are placed on the grid, then masked for the most scannable balance of black and white.
5. Render and export. The grid is drawn to a canvas at your chosen pixel size and dark color; Download saves it as a PNG.

Technical Details

Standards & references

• ISO/IEC 18004 — the international standard for QR Code symbology — module layout, the four error-correction levels, and the 40 versions from 21×21 to 177×177 modules.
• Error-correction levels L, M, Q, H — Reed–Solomon recovery of roughly 7, 15, 25 and 30% of the code respectively; this tool generates at level H.
• Quiet zone — the standard asks for a clear margin of at least four modules around the code so scanners can locate it.

Accuracy & Limitations

Codes are generated at level H, so they tolerate damage well but are denser than a level-L code holding the same text. A long URL makes the pattern busier and the modules smaller — shorten the link first if you want larger, easier-to-scan squares.

The downloaded PNG is the bare symbol. Keep a white margin — the quiet zone — of about four modules around it wherever you place it, or some scanners will struggle to lock on.

Contrast matters. The background is locked to white, but a pale dark color can stop the code scanning. Choose a dark, saturated color; plain black is safest.

It is a static QR. Once it is printed you cannot change where it points or see how many times it was scanned. Editable destinations and scan analytics need a dynamic-QR service with a backend — a different kind of tool.

PNG is raster, so enlarging the file too far softens the edges. For big prints, generate at a larger pixel size from the start rather than scaling up afterwards.

Real-World Use Cases

When to use it — and when not to

Need to edit the link later or see scan counts? That needs a dynamic-QR service with a backend. Want a 1-D retail or inventory code instead of a 2-D one? Use the barcode generator, which outputs scalable SVG.

Frequently Asked Questions

References

• DENSO WAVE — QR Code versions and information capacity
• ISO/IEC 18004:2024 — QR Code bar code symbology (ANSI Blog)
• qrcodejs — cross-browser QR code library (GitHub)
• What is a QR code quiet zone and why it matters

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