Code 128 is the dense, high-density barcode used on shipping labels, product packaging and asset tags because it can encode the full ASCII range in a compact form. This generator turns your text into the corresponding sequence of symbols, automatically switching between Code Set B for letters and punctuation and Code Set C for long runs of digits (which pack two digits into one symbol). It then computes the modulo-103 check character — the weighted sum every scanner verifies — appends the stop pattern and draws the black-and-white bars pixel by pixel onto a canvas.
You can adjust the bar height and module (thin bar) width, optionally print the human-readable text underneath, and download the finished barcode as a crisp PNG for printing or embedding. Any character outside the printable ASCII range is rejected with a message. Nothing is uploaded — the encoding, check-digit math and rendering all happen locally in your browser.