QR Code Generator

Enter a URL, text, phone number or anything else to generate a scannable QR code instantly. It's created in your browser — nothing is uploaded — and you can download it as a clean PNG with no watermark.

Enter text or a URL and press Generate QR code.

How QR codes store data

A QR (Quick Response) code is a 2D barcode: a grid of black and white squares called modules that encode data both horizontally and vertically. The three large squares in the corners are finder patterns that let a camera locate and orient the code. The rest of the grid holds your encoded text plus built-in error-correction data.

text → bytes → Reed–Solomon ECC → module grid

The encoder converts your text to bytes, adds Reed–Solomon error-correction codewords, and lays everything out on the smallest grid (version) that fits. More data means a denser grid.

Worked example

Encoding the URL https://calcool.us/:

Encode: the URL becomes a stream of bytes.
Protect: error-correction codewords are appended.
Render: the result is drawn as a grid you can scan with any phone camera.

Error correction levels

QR codes can still be read even when partly damaged or obscured, thanks to four error-correction levels: L (~7%), M (~15%), Q (~25%) and H (~30%). Higher levels recover from more damage but make the code denser. Level M is a good default; choose H if the code will be printed small, placed on a curved surface, or might get scuffed. Keep a quiet (white) margin around the code so scanners can find it.

Tip: need to make a URL itself safe to embed first? Use the URL encoder.

Frequently asked questions

Do these QR codes expire?

No. The codes are static — the data is encoded directly into the image, so they work forever and never expire. There's no tracking redirect and nothing depends on this site staying online.

Can I download the QR code?

Yes. After generating, click Download PNG to save a clean, watermark-free image you can print or embed anywhere. The code is drawn on a canvas in your browser.

What can I put in a QR code?

Anything text-based: a website URL, plain text, a phone number (tel:), an email (mailto:), Wi-Fi credentials or contact details. URLs are the most common use.

Which error-correction level should I choose?

M (15%) suits most uses. Choose H (30%) if the code will be printed small, placed on a curved or textured surface, or might get partly damaged, since it tolerates more obstruction.

MB
Mustafa Bilgic · Editor, Calcool
QR codes are generated entirely in your browser with a self-contained encoder (no external service) and follow the ISO/IEC 18004 QR Code standard. Everything runs in your browser — nothing you enter is uploaded, logged or stored.

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