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DevTools / Gerador de códigos QR

Gerador de códigos QR

A QR code is the shortest path between something physical and something digital, and the details decide whether it works: the error-correction level determines how much of the code can be obscured before it stops scanning, the quiet zone is the margin that many generators omit and many scanners require, and the payload format is what makes a code open a Wi-Fi network rather than merely display a string. This generator covers the common payload types, renders at any size with a configurable margin, supports a centre logo with the error-correction implications stated, and decodes an uploaded screenshot so you can check a code someone else produced.

Roda inteiramente no navegador — nada é enviado.

Encoded payload — 28 bytes

Decode a QR code from a screenshot

ou solte um arquivo aqui

L lowest · M default · Q · H highest

Centre logo

Como funciona

A QR code is a two-dimensional grid of modules — the black and white squares — with three large finder patterns in the corners that let a scanner determine orientation and scale. Data is encoded with Reed-Solomon error correction, which adds redundant codewords so that a damaged or partly obscured symbol can still be decoded. There are four levels: L recovers about 7 percent of the symbol, M about 15 percent, Q about 25 percent and H about 30 percent. A higher level means more redundancy, which means more modules for the same payload, which means a denser code that needs more space to scan reliably.

The payload is just text, and the format of that text is what gives the code its behaviour. A plain URL opens a browser. A string beginning WIFI: with the right fields joins a network. A vCard payload adds a contact when scanned. The MECARD and vCard formats are both used for contacts and are not interchangeable across all scanners. Field values must be escaped: a semicolon, comma or backslash inside a Wi-Fi password or a contact name terminates the field early and produces a code that scans into garbage, which is why escaping is applied automatically here rather than left to the user.

Capacity is the constraint that shapes every other decision. A QR symbol has a maximum of 177 by 177 modules at version 40, and the amount of data it can carry depends on the error-correction level and on the character set: numeric data packs most densely, then alphanumeric, then bytes, then kanji. In practice a URL of around 100 characters at level M fits comfortably, while a 500-character payload produces a very dense code that a phone camera struggles to resolve on a screen or a printed label. Shorter is better, and a URL shortener is often the right answer for a long link.

Scanning reliability is a physical property as much as a digital one. The quiet zone — the margin of blank space around the symbol, specified as four modules — is required by the standard and is the first thing a badly designed poster removes. Contrast matters more than colour: dark modules on a light background scan reliably, while an inverted code works on some scanners and not others. Placing a logo in the centre overwrites modules, which is why it should be used only at level Q or H, and why the logo should cover no more than a quarter of the width.

Casos de uso comuns

  • Put a Wi-Fi network's credentials on a card so guests can join without typing a password.
  • Create a vCard code for a conference badge or a business card.
  • Generate a code for a restaurant menu, a product page or an app download link.
  • Encode a location or an event with its start and end times for a poster.
  • Decode a QR code from a screenshot to check where it actually points before scanning it.
  • Produce an SVG code for print at large sizes without the pixelation a bitmap would show.

Última atualização: 2026-10-14 — o corpo do artigo é exibido em inglês; a interface está traduzida.

Perguntas frequentes

Which error-correction level should I use?

Level M is the usual default and balances density against robustness. Choose Q or H when the code will be printed on a curved or reflective surface, when it may be partly obscured, or when you are placing a logo in the centre. Choose L only when the payload is long and the scanning conditions are good, since it produces the least dense code. Higher levels always mean a denser symbol for the same data, which is a real trade: a code that is too dense to resolve reliably is worse than one that is slightly less robust.

Should I add a logo to the centre?

Only at error-correction level Q or H, and only if the logo covers a quarter of the width or less. A logo overwrites data modules, and the error correction is what allows the scanner to reconstruct them; at level L there is barely enough redundancy for ordinary wear, let alone a deliberate hole. Keep the logo away from the three finder patterns in the corners, which the scanner needs intact to orient itself, and always test the printed result with several phones before committing to a print run.

Why is the margin around the code important?

Because the specification requires a quiet zone of four modules — the width of four small squares — of blank space on every side, and scanners rely on it to distinguish the symbol from its surroundings. Without it, a scanner may fail to find the edges of the code or may mistake nearby text or a border for part of it. Many generators default to no margin to make the image look tidier, which is why a code that works on screen fails when printed on a busy poster. The margin is configurable here and defaults to the specified four modules.

Can I scan a QR code without a phone?

Yes — upload a screenshot or an image containing a code and it will be decoded in the browser, showing the exact payload including the Wi-Fi password or URL it contains. That is worth doing before scanning an unfamiliar code, since the payload is visible without visiting whatever it points at. Decoding runs locally through the same image APIs the camera path would use, so the image is never uploaded.

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