Processed locally
Your input stays in this browser.
A symbol is a direct record
QR Decode turns supplied link, text, e-mail, telephone, SMS, WiFi, contact, event, location, or WhatsApp data into a static QR symbol. The symbol carries that payload itself; it is not a label pointing to our redirect service. That design keeps the scan independent of an account or a campaign dashboard, but it also makes the exported image a record that must be replaced when its contents change.
The geometry behind a printable code
A QR image is a square grid of modules. Its outside width can be expressed as (modules across + 8 quiet-zone modules) × printed module width: four clear modules are required on each side of the encoded square. The calculation assumes an undisturbed pale margin and square modules. It does not turn pixels into a universal print size, because payload length, error-correction level, printer spread, material, camera focus, and viewing distance all affect whether a particular symbol is easy to capture.
A worked label calculation
Consider a 29-by-29-module symbol printed with 0.8 mm modules. Its encoded square is 29 × 0.8 = 23.2 mm wide. Adding eight margin modules gives 37 × 0.8 = 29.6 mm for the complete mark. A designer who measures only the dark-looking square may reserve 23.2 mm and accidentally crop the 3.2 mm border on each side. The arithmetic is useful for allocating space; it is not evidence that 0.8 mm modules will survive a given press, laminate, or scan distance.
What happens in the browser
Generation, preview, logo compositing, and downloads run in the browser. The text entered for a payload and an uploaded logo are not sent to our server, and the tools do not require an account. A static output also contains no later editing control, scan counter, or destination replacement mechanism supplied by this site. Keep the source values with the exported asset so that a revised menu address, password, date, or contact detail can be regenerated deliberately rather than reconstructed from a screenshot.
What the read-back check actually tests
Each offered design is rendered and decoded again locally before it is presented. For a finished image, the check asks a narrow question: can a decoder recover the expected payload from these pixels? It can reveal a logo that obscures modules, weak separation between foreground and background, or damage introduced during export. It does not sample every phone camera or predict a curved bottle, glare on a laminate, ink gain, a fold, a distant poster, or a scanner application that does not support the payload type.
Approval needs the final object
For a printed job, compare a plain control and the final branded artwork at the intended size. Decode the export first, then scan a physical proof under the distance, light, and angle the audience will encounter. Inspect the recovered content rather than merely accepting that the camera reacted: a readable old URL is still the wrong result. A successful proof supports that one file and production condition; any new colour, crop, logo, payload, or substrate needs its own check.
Corrections
Report a problem at [email protected]. Include the browser and reproduction steps, but do not send private QR contents.
How the site is funded
The site carries advertising served by Google, which is disclosed in the privacy policy and the cookie notice. Advertising supports the site; QR payloads and uploaded images remain local to your browser.
A worked geometry example
A QR matrix of 33 by 33 modules printed with a 1 mm module pitch occupies a 33 mm encoded square. Its required four-module quiet zone adds 4 mm on each edge, so the complete panel is 41 mm. If a layout reserves only 33 mm because the designer measured the dark area, the margin is lost even though the matrix itself was not resized. The calculation describes space allocation, not a guaranteed printing minimum: a 1 mm module can still be affected by paper, ink spread, glare, focus and distance.
What a local result means
The browser can generate a symbol and decode its rendered pixels again without uploading the payload. A successful local read-back means this browser recovered the expected bytes from that rendered version. It does not say that a destination exists, that a contact record is current, that every scanner supports an event or Wi-Fi payload, or that a printed object will be readable. Those are distinct questions. Keeping them separate prevents a green on-screen result from being misused as approval for a production run.
Example: checking a changed menu link
Suppose a restaurant changes its menu from example.org/summer to example.org/menu. A static QR image cannot be retargeted by this site after download. Generate a new asset from the approved address, decode the downloaded image, place that exact file into the table-card artwork, and test a printed proof. Reusing last season's image because it still scans is not a repair: it merely preserves an old, readable destination. Keep the source value and final file together so the replacement can be reviewed later.
Example: when a logo is the variable
When a plain black-on-white code reads but a branded version does not, first compare those two files with the same payload and error-correction setting. A pale logo panel removes modules even where the visible logo is transparent; a border or coloured background may also reduce the clear margin. Remove or shrink the visual treatment before changing the encoded text. If the plain control fails as well, the investigation belongs with the input or encoder. This controlled comparison is more informative than repeatedly changing colours, size and payload together.
Where the QR rules come from
QR Code symbol characteristics, dimensions, encoding and error-correction rules are specified by ISO/IEC 18004:2024. For retail-oriented 2D implementations, GS1's implementation guidance describes the module as the X-dimension and states a QR quiet zone of four X-dimensions on each side. QR Decode uses those facts to explain geometry; it is not a certification body, a GS1 registry or a verifier for a particular supply-chain workflow.
How to use the site safely
Generate only content you are entitled to publish and retain a readable non-QR fallback where people may not have a camera or network access. Treat an unfamiliar QR code as an untrusted link: decode it first and use a known official route before entering credentials or payment information. For a code you created, check the exact final file and the final physical object. For an operational barcode, retail symbol or regulated label, test with the actual receiving system and follow its owner’s specifications rather than relying on a consumer-phone scan.
A practical hand-off record
When a code goes to another person, provide the source payload, the generated asset, its intended outside size, the approved page artwork and the test result. That is more useful than a message saying only that the QR code was checked. The recipient can decode the file again, preserve its proportions in the layout and identify whether a later change was to content, branding or print process. For sensitive data, use a harmless test value when requesting support; the tools do not need you to send private QR contents to explain a reproduction fault.