Website and link QR code generators

Only if the shortener runs on a domain you control. A shorter string does produce a sparser, more forgiving pattern, which is a real benefit on small prints. But a third-party shortener inserts a company between your printed material and your content, and those links have expired often enough to make it a poor trade for anything long-lived. A short path on your own domain gives you the same density win with none of the dependency.

Yes, if the app registers a universal link or app link for that address, which most large platforms do. Encode the ordinary web URL rather than a custom scheme like myapp colon slash slash, because the web URL falls back to a browser page when the app is not installed while a custom scheme just fails with an error. Test on both platforms, since Android and iOS resolve these associations differently.

The code keeps working and leads to a missing page, which is the most common way printed material goes stale. There is no way to detect it from the pattern. The defence is to encode a stable address that you redirect on your own server, so that moving the underlying file is a one-line change rather than a reprint. Treat the encoded URL as a permanent contract.

It is a genuine option and underused. A serial number on equipment, wiring instructions inside a panel, a short safety notice or a reference code all resolve on the device with no connection, no server and nothing to maintain. The limit is length: text lives inside the pattern, so a few hundred characters is the practical ceiling before the grid gets too dense to print small.

Because it is carrying more characters. A Wi-Fi credential is typically forty or fifty characters, while a URL with campaign parameters can be double that, and every character costs modules. If two codes are printed at the same size and one scans noticeably worse, the payload length is almost always the reason. Trimming the URL is the fastest fix available.