How much data can one QR code hold?
The encoder walks versions 1 through 40 and picks the smallest that fits, which at version 40 with Low error correction is 2,953 bytes, and about 1,270 bytes at High. Long before you hit that ceiling the code becomes impractical: a version 40 grid is 177 by 177 modules and needs to be printed very large, or scanned very close, to be readable at all. If your payload is long, put it behind a short URL.
What do the version, module, and mask numbers under the code mean?
Version is the size class (1 to 40), and the module count is the grid size, which is always version times 4 plus 17, so version 3 is a 29 by 29 grid. The mask is which of the 8 standard XOR patterns was applied to break up large blocks of same-coloured modules, chosen automatically by the spec's penalty scoring. All three are diagnostics: they tell you how dense your code is and therefore how large you need to print it.
What does a Wi-Fi QR code actually contain?
A plain-text string in the form WIFI:T:WPA;S:MyNetwork;P:mypassword;; with special characters escaped. It is not encrypted and not signed: anyone who can photograph the code can read the password out of it. That is fine for a guest network printed on a card in your cafe, and a bad idea for your main network on a poster by a window.
Can I put a logo in the middle?
Not with this tool, which produces a clean spec-conformant code. If you overlay a logo yourself in a design tool, raise the error correction to High first, keep the logo under about 20 percent of the code's area, and then test the result on both an iPhone and an Android device before you print a thousand of them.
Can I change what the code points to after I have printed it?
No. The destination is encoded directly into the pattern, so a printed QR is permanent. If you need to change the target later, encode a short URL that you control and redirect it, which is what commercial "dynamic QR" services are selling. The trade is that the redirect service can then see and log every scan.
Which content types are supported?
Nine: plain text or a link, Wi-Fi credentials, an email (mailto with subject and body), a phone number, an SMS, a contact card (vCard 3.0), a WhatsApp chat, a geographic location, and a calendar event (an iCalendar VEVENT block). Each one builds the standard payload string that phone cameras recognise, so scanning a contact code offers to add a contact rather than showing a wall of text.
Is this QR code generator really free?
Yes, and free here means free: no signup, no watermark, no trial that expires the code later. Static codes cost nothing to generate and nothing to keep working, which is exactly why this page can promise that.
Do QR codes from this tool expire?
No, ever. The content is encoded directly into the pattern, so the code works for as long as its destination exists. Codes that "expire" come from services that route scans through their own domain and turn the redirect off when the free trial ends.
How do I make a QR code for a restaurant menu?
Host the menu at a stable URL, ideally a short one, encode it as a link code, and print it with the quiet zone intact. Because the code is static it will not die when a service changes its pricing, but it also cannot be re-pointed later, so encode a URL you control.
How do I make a QR code for a business card?
Use the contact type. It encodes a vCard with your name, phone, email, and company, and a scanned vCard opens straight into the add-contact screen on both iPhone and Android. Keep the fields short: every extra character makes the printed code denser.
How big should a printed QR code be?
The rule of thumb is scan distance divided by ten: a code scanned from 25 cm can be 2.5 cm wide, a poster scanned from 3 metres needs about 30 cm. Denser codes (longer payloads or High error correction) need to be larger for the same distance, which is another reason to shorten the URL first.