QR Code Generator

A QR code is not a picture that gets looked up somewhere — it is the data itself, encoded directly into the pattern of black and white squares using Reed-Solomon error correction and a defined bit-layout standard, so a scanning app decodes the content immediately from the image, with no network request required to figure out what it says. This is a meaningfully different design from a shortened URL, which requires a lookup against a database somewhere to resolve into the real destination — a QR code encoding a URL directly *is* that URL, character for character, the instant it is generated, and remains exactly that indefinitely.

This directness is precisely why a QR code generated this way never expires and cannot be redirected somewhere else after the fact by whoever created the service — there is no external service in the loop at all to shut down, start charging for, or repoint. A generator that instead encodes its own short redirect URL into the code, rather than your actual content, is introducing exactly that dependency, quietly, and is the version of "free QR code" that has a real track record of expiring or beginning to charge once enough people have printed the code onto something physical.

Every QR code embeds redundant data specifically so it can still be read correctly even when part of the printed pattern is scratched, dirty, poorly lit, or deliberately obscured by a logo placed over the middle. Four standard levels exist, and choosing a higher one is not free: the same underlying content requires a visually denser, more complex pattern at a higher error-correction level, since more of the code's total capacity is spent on redundancy rather than on the actual encoded data. Level L tolerates roughly 7% damage and produces the simplest, least dense pattern for a given piece of content; level H tolerates up to 30% damage but produces a noticeably busier pattern for the same content, which is both harder to scan from a distance and the reason it is specifically recommended when a logo will cover part of the code — the higher redundancy budget is what leaves enough of the code intact once the logo has visually removed a chunk of it.

A QR code that scans instantly on a phone screen at arm's length can fail completely printed at the same size on a poster meant to be scanned from three metres away, because the physical size needed scales directly with how far away the scanning phone will be — the rule of thumb is that the code's printed width should be at least a tenth of the intended scanning distance. A code meant to be scanned from 20 centimetres away needs to be roughly 2 centimetres wide; one meant to be scanned from across a room, several metres away, needs to be proportionally much larger. Shorter encoded content also helps at distance for a related reason: less data produces a visually simpler pattern with larger individual squares, which remains legible to a camera from further away than a dense pattern encoding a long string would.