Two ways in
Lists and sequences
A pasted list suits values you already hold — a column copied out of a spreadsheet, an export of SKUs, a set of GTINs from a supplier. One value per line, blank lines ignored. This is the mode to use when the values are not predictable, because nothing is invented for you.
A generated sequence suits values that do not exist yet: numbering a new run of asset tags, labelling storage bins, or issuing serial numbers. Set a prefix, a starting number, how many you need, the step between them and how many digits to pad to. SKU- starting at 1, twelve of them, padded to four digits gives you SKU-0001 through SKU-0012.
Padding matters more than it looks. Unpadded numbers sort as text into 1, 10, 11, 2, 20 — which turns any spreadsheet or file listing into a mess. Padding to a fixed width keeps numeric and alphabetical order the same, so pick a width with room to grow and stay with it.
Bad rows
What happens to values that do not fit
Every value is validated against the format you chose before anything is drawn. Valid ones are rendered; the rest are listed underneath with the specific reason — a wrong check digit, a character the symbology cannot carry, the wrong number of digits. Nothing is silently dropped and nothing is silently corrected, because a barcode quietly encoding something other than what you pasted is worse than no barcode.
A common surprise: a column of twelve-digit numbers set to EAN-13 will pass, because the check digit is calculated and appended. The same column set to UPC-A will pass too, but as eleven digits plus a computed check. Those are different codes. Check one printed value against your source data before printing the batch.
Getting the files
Sheet, PNG or individual files
The sheet download puts every symbol on a single SVG at the column count you pick, ready to place in a label template or send to a printer. Because it is vector, you can scale the sheet to any label pitch without softening the bar edges. The PNG version is there for tools that will not accept vector artwork; it is rendered at 2× and should not be enlarged afterwards.
Individual downloads sit under each symbol, named after the value they encode, which is what you want when the barcodes are going into separate product listings or artwork files rather than onto one page.
There is no ZIP download. Building archives in the browser would mean pulling in a compression library, and for a few hundred small SVG files the sheet plus per-item downloads covers the same ground without the extra weight on every page load.
Practical limits
How many is sensible
The cap is 500 values per run. That is a browser limit rather than a licensing one: each symbol is real SVG in the page, and several thousand of them makes scrolling sluggish on a phone. For a larger job, split it into runs — a spreadsheet column is easy to slice — or generate the sheet in batches and combine them in your label software.
Sequence generation also has a quiet trap worth naming: if you are producing retail GTINs, the numbers must come from a prefix licensed to you, and each one must carry its own correct check digit. Generating a tidy-looking sequence of thirteen-digit numbers does not make them yours. For internal codes — bins, tools, boxes, jobs — none of that applies and you can number them however you like.
Questions
Frequently asked questions
How many barcodes can I generate at once?
Up to 500 per run. Split larger jobs into batches; the limit is about keeping the page responsive, not about licensing.
Can I download them as a ZIP?
No. You can download the whole run as one SVG or PNG sheet, or download individual symbols one at a time from under each preview.
What happens to invalid values in my list?
They are listed separately with the exact reason, and nothing is silently corrected. Valid values still generate normally.
Can I generate a sequence of EAN-13 numbers?
You can generate the digits, but only use them if the prefix is licensed to you. The check digit is calculated for each value automatically.
Why pad numbers with leading zeros?
So text sorting and numeric sorting agree. Without padding, item 10 sorts before item 2 in most spreadsheets and file listings.
Are my values uploaded anywhere?
No. The list stays in your browser; every symbol is rendered on your own device. Optional Analytics is separate and only starts after consent.