From a Spotify link to a 3D-printable tag — paste, tweak, save. Everything runs in your browser; nothing is uploaded.
For a scannable print, use two colours (dark plate, light bars) — a single-colour tag usually won't scan. The colour-change layer sits at z = base thickness.
The Save button above builds the STL right here in your browser. If you'd rather adjust the model — change any dimension, switch to the engraved style, or fine-tune the design — this page also produces fully parametric OpenSCAD code. Copy it, open it in OpenSCAD (it's free), change any parameter, then F6 → File → Export → STL.