Bulk QR code generator
Up to 500 QR codes in one pass, from four kinds of input: a number sequence with a prefix and suffix, a CSV or TSV file you upload, a list you paste one per line, or generated test data when you need plausible values rather than real ones. Every row is validated before anything is generated, so a malformed line is reported next to its row number instead of silently producing a code that encodes an error message.
The download is a ZIP containing every image plus two manifests — a CSV and a JSON — that record what each file encodes, its version, its error-correction level and its filename. The manifests are the part that makes a batch usable a week later: a directory of 500 PNGs with no index is data you have to re-derive, and a batch you cannot map back to its inputs is not a fixture.
Filenames are made safe and made unique. Characters a filesystem would reject are replaced, Windows reserved device names are avoided, and collisions get a numeric suffix rather than overwriting each other — which is what happens when 500 rows share a value and a naive exporter writes them all to the same name.
Generation is chunked with a progress indicator and can be canceled, because 500 codes at a large module size is real work for a browser tab and a frozen page with no way out is worse than a slow one. Nothing is uploaded: the CSV you choose is read locally by the browser, not sent to a server.
The obvious use is a batch of asset tags, table numbers or ticket codes. The testing use is load: 500 distinct symbols is enough to find out whether a scanning app leaks memory, mis-handles a duplicate, or slows down as its history grows.