How long does a QR code last?
By definition, a QR code does not have a limited validity period and thus cannot “expire”. Consider it as a simple container that stores information. In theory, a piece of paper with a printed QR code may become dirty or get damaged; an HDD that contains a digital image of a QR code may get broken. However, as long as a QR code is readable, it keeps the same information encoded initially. But instead of information itself, QR code may encode an URL that leads to a page with some specific information. Such a link may expire or a page might become unavailable or information on this page may change or turn irrelevant. In this sense, you can say that QR code has got "expired".
Do QR codes contain personal information? Is it safe?
QR codes store exactly the information passed as input during their generation process. If you have a piece of paper with a printed QR code, it does not contain any additional information besides the data inputted for encoding. If you take a photo of a QR code using your smartphone, it may attach personal data to the photo itself, such as name, location, or any other information that can be derived from smartphone memory. Concerning personal vaccination passports/certificates, in some cases, QR codes may contain personal data that you might want to keep private. In general, such QR codes simply store links to external pages, and data on such pages are usually anonymized. To verify this, you may check information on the official website of your local authorities or control what exactly is encoded in your QR code using the Aspose.Barcode QR Code scanner.
What information can I put into barcode?
It is usually letters and numbers. For some barcodes you can choose a specific set of characters(symbology). This information usually represents some description of an item on what barcode is placed.
Can barcode be very small?
It can be reasonably small. For example 1x1 cm for 2D barcode. But in the smaller barcode you can encode less information. And you also should use a printer with higher resolution.
How much data can barcode contains?
It is usual to be about 25 characters for 1D barcode and about 2000 for 2D one. Of course the more characters you encode the bigger is barcode. 1D barcode could became impractically wide if it is more than 15 characters encoded.