What can I encode in a QR code?

Any text: URLs, notes, email addresses, phone numbers, and formatted strings such as Wi-Fi credentials (WIFI:T:WPA;S:Name;P:Pass;;) or vCards. The tool encodes exactly what you type, so a Wi-Fi code must use that WIFI: format for phones to recognise it.

How much data can a QR code hold?

At level L the largest code, version 40, holds 7,089 digits or 4,296 uppercase alphanumeric characters or 2,953 bytes. Digits are the cheapest, lowercase letters are the most expensive, so a realistic URL uses a fraction of the headline number. Raising the error correction level reduces every one of those figures.

Why use one mode for the whole string?

A single mode keeps the output small, fast, and easy to audit. The trade-off is capacity: the tool picks the densest mode the entire string fits, so a single lowercase letter in an otherwise uppercase string forces the whole thing into byte mode. Splitting a string across modes would squeeze in more characters, at the cost of a longer, denser code that is harder to scan.

Will non-Latin text work?

Usually. Text outside ASCII is encoded as UTF-8 bytes with no ECI header, which is what most readers assume. A minority of scanners interpret those bytes using a different encoding and show mojibake instead. If that matters to you, keep the content to ASCII or test on the specific readers you need to support.

What error correction level should I use?

M (15%) is the best balance for most uses. Q (25%) and H (30%) are worth the extra density for printed items that get handled, since a higher level recovers more damaged modules at the cost of a finer code. L (7%) holds the most text and survives the least. Higher error correction repairs damage to the modules themselves — it cannot rescue glare, motion blur, or a code printed too small to resolve.

Can I invert the colours, light on dark?

You can, and the tool will let you, but treat it as a risk. A light-on-dark code reads on many modern phones and fails on plenty of others, especially older readers and some built-in cameras. If you need inverted colours, scan it on every device you care about before committing to print.

How large should I print it?

Judge it by module size rather than overall width: keep each module at 0.5 mm or larger, which is roughly what a phone camera needs to resolve. A version 40 code needs about 83 mm across at that module size, while a version 4 code needs only about 40 mm. The tool warns when a code at a given width would fall below this, and printing larger is always the easier fix.

Why does my QR code not scan?

In order of likelihood: the module size is too small on screen or in print; the contrast between foreground and background is under 4:1; glare or a curved surface is distorting the modules; the code is a dense high version; or the quiet zone around it was cropped. Raise contrast, make it bigger, flatten the surface, and keep the border. No QR code is guaranteed to scan in every condition, so always test on the device you intend to use.

What is the quiet zone and why is it there?

It is the four-module-wide blank margin the specification requires on every side of the code. Scanners use it to find the code's edges and to judge where the dark area starts. It is included in both the PNG and the SVG, and cropping it is one of the most common reasons an otherwise perfect code will not read.

Does anything leave my browser?

No. The encoder is pure TypeScript running on your device, so the text is never sent anywhere and is never logged. This matters for codes carrying Wi-Fi passwords or private links. Once the page has loaded, the tool works offline.

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QR Code Generator

QR codes generated in your browser

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Free forever — no sign-up, nothing uploaded. Files never leave your device.

braincoder.app/use/qr-code-generator

QR Code Generator

QR codes generated in your browser

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Local processing

Processing time depends on your input and device.

About this tool

Turn any text, URL, or Wi-Fi configuration string into a QR code. Customize colors, error correction, and size, then download as PNG or SVG. Nothing is uploaded.

The BrainCoder QR Code Generator turns text or a URL into a QR code entirely inside your browser. There is no Generate button and no server round-trip: the code is rebuilt as you type, and the text never leaves your device.

Encoding is written from scratch in TypeScript rather than delegated to a third-party library, and it covers the whole standard — versions 1 to 40 and all four error correction levels, with Reed-Solomon error correction and ISO penalty scoring for mask selection. Pick foreground and background colours, choose an error correction level, and set the PNG width.

Download a PNG for screens and documents, or an SVG when the code is going to print: the SVG is vector, so it scales without resampling, while the PNG is a raster image that is only sharp at the pixel size you exported.

The tool is deliberately candid about its limits. Error correction recovers damaged modules, not glare or blur; printing needs each module to stay at least 0.5 mm; the four-module quiet zone is part of the image and must not be cropped; and a single mode is used for the whole string, so mixed or non-ASCII text holds fewer characters than the headline figure.

Key features

Everything you get with QR Code Generator — no premium upsell.

Encodes in the browser from scratch — no library, no uploads

Full standard support: versions 1 to 40 and levels L, M, Q, H

Reed-Solomon error correction with ISO penalty-based mask selection

Two outputs: PNG raster at an exact integer module scale, and SVG vector

Live warnings for low contrast, print size, and dense versions

Shows the version, size, mode, and mask it actually chose

Nothing leaves your device, so it keeps working offline

How to use QR Code Generator

Follow the steps below to use the tool.

1
Enter your content
Type or paste any text, URL, email address, phone number, or Wi-Fi configuration string (WIFI:T:WPA;S:Name;P:Pass;;). The code updates as you type. The box starts empty on purpose, so what you see is what you encoded.
2
Choose an error correction level
L (7%), M (15%), Q (25%), and H (30%) trade capacity against tolerance for damage. M suits most uses; Q and H are worth the extra density for stickers and packaging; L holds the most text but survives the least.
3
Check the warnings before you commit
The panel warns when your colours have poor contrast, when the code is dense enough that screens and cheap printers lose modules, and when the chosen version will be too fine to print. Fixing these is usually easier than upgrading your scanner.
4
Scan it with your own phone
Before printing in bulk, scan the preview with the phone you expect to be used. This is the only test that matches your actual camera, screen brightness, and viewing distance.
5
Download
Use the PNG for screens, chat, and documents. Use the SVG for anything that will be printed or resized, since it stays sharp at any size and any resolution.

Still free, still private — your files never leave your device.

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QR Code Generator

About this tool

Key features

How to use QR Code Generator

Enter your content

Choose an error correction level

Check the warnings before you commit

Scan it with your own phone

Download

Frequently asked questions

Related tools

How-to guides