A Data Matrix code, very small and very sturdy
Draw a Data Matrix code, the one on parcels and small parts: as much content as a QR code in far less room.
Asked for with
"type": "data_matrix"
In plain words
Written for anybody. It says what this puts on a sheet of paper, and asks nothing of you beyond that.
This is the small square of dots found on parcels, medicine bottles and machined parts. It carries roughly as much as a QR code but in far less room, which makes it the favourite of tiny labels. You give the text and the frame, and the square is drawn with its white margin on all four sides. It copes well with dirt and light scratches, which helps when the label travels.
For a developer
Written for somebody who writes the calling program: the model, the units, and the settings that carry the weight.
Encoding follows the ASCII scheme at ECC 200, the standard's modern correction. The symbol and its quiet zone on all four sides fill the rectangle's width, anchored at the lower-left corner: the width commands, the rectangle's height is headroom. The symbol's size is the smallest that carries the given text; beyond the largest square symbol, the answer is 400. Like the other codes, the item draws the symbol alone.
Every key, with its default
The reference: which keys are required, which are optional, what each one defaults to and which combinations the server declines.
Required keys: content, a string; rect. Optional: pages, an array of one-based integers, default empty; transform, six numbers; rotate, degrees counter-clockwise about the centre of the box; layer, the name of a declared layer. Cross refusal: transform together with rotate. The encoding scheme and the correction level are fixed: the wire exposes the content and the box.
A whole request that draws it
Post this as it stands and a PDF comes back. Nothing has been left out of it.
{
"items": [
{
"type": "data_matrix",
"content": "SN:2026-08-08/ACME-4472",
"rect": {"llx": 72, "lly": 700, "urx": 132, "ury": 760}
}
]
}Barcodes and square codes
A barcode of vertical bars A square QR code, read with a phone An Aztec code, with no white margin around it A PDF417 code, carrying a whole form
Where to go next
Every key of a request, in one page The other twenty things you can draw
Glossary
- standard
- A rule argued out in committee, published under a number anybody may buy and read, and identical for every firm claiming it. A claim to follow one can therefore be checked against the text. A way of working that merely spread because it worked is a habit of the trade: useful, widespread, and answerable to no text at all.
- QR code
- The square of black and white dots you point a phone at: on a poster, on a restaurant table, at the foot of a bill. It carries a web address, or the exact details of a payment, so nobody has to type anything in. On an invoice it turns paying into one tap.
- layer
- A named group of things drawn on a page that a reader can switch on and off, like tracing paper laid over a plan. A drawing can hold its measurements on one and its notes on another, and a layer can be set to show on screen and stay off the printer.