I'm a product developer, but with some regularity I need to create or edit UPC barcodes when I am doing packaging design for clients. I have been frustrated with the options for UPC Barcode generation. Most of the online ones that I have found (for free) spit you out a raster image that isn't really useable if you're doing anything more than putting a junky-looking white sticker on the back of a box or hang tag. There is/was a good plug-in for EAN 13, but not UPC-A.

It dawned on me to use an LLM and my almost non-existent knowledge of coding to make a script that can run in Adobe Illustrator. After an hour of LLM jiu-jitsu (mostly me getting choked out), I have the following working prototype:

BTW - you'll need to create a new plain text file and save it as something memorable, like "generateUPC.jsx" in a location that you can get to easily. ( I have a folder of document templates and swatch libraries in the cloud, so I keep it there). Once you save that, then go into Ai and file>Scripts>other scripts (ctrl+f12); select your new jsx file that you just made and then enter the info in the prompts. This should spit you out a working UPC barcode with the UPC number below it. Also whatever human-readable text you want to put below the number. It generates a grouped object and text more or less in the center of the Ai working area (so you probably need to go looking for it).

And I welcome your critique and edits. I have next-to-zero understanding of programming, so you won't hurt my feelings. FYI, I did test it with some things from the pantry and a UPC scanner app on my iPhone; seemed to work fine!

-----Copy everything below this line into the notepad file -------

// UPC-A Barcode Generator for Adobe Illustrator
// This script creates scannable UPC-A barcodes with human-readable text

// UPC-A encoding patterns
var leftPatterns = [
    "0001101", "0011001", "0010011", "0111101", "0100011",
    "0110001", "0101111", "0111011", "0110111", "0001011"
];

var rightPatterns = [
    "1110010", "1100110", "1101100", "1000010", "1011100",
    "1001110", "1010000", "1000100", "1001000", "1110100"
];

var guardPatterns = {
    start: "101",
    middle: "01010",
    end: "101"
};

function createUPCBarcode() {
    try {
        // Get UPC number from user
        var upcInput = prompt("Enter 12-digit UPC number (digits only):", "");
        
        if (!upcInput) {
            alert("Script cancelled.");
            return;
        }
        
        // Get human readable text from user
        var humanReadableText = prompt("Enter human readable text (optional - press Cancel or leave blank for none):", "");
        if (humanReadableText === null) {
            humanReadableText = ""; // User pressed Cancel
        }
        
        // Clean and validate input
        var upcNumber = upcInput.replace(/\D/g, ''); // Remove non-digits
        
        if (upcNumber.length !== 12) {
            alert("Please enter exactly 12 digits for UPC-A barcode.");
            return;
        }
        
        // Calculate check digit to verify
        var calculatedCheck = calculateCheckDigit(upcNumber.substring(0, 11));
        if (parseInt(upcNumber.charAt(11)) !== calculatedCheck) {
            var useCalculated = confirm("Check digit doesn't match. Use calculated check digit (" + calculatedCheck + ")?");
            if (useCalculated) {
                upcNumber = upcNumber.substring(0, 11) + calculatedCheck;
            }
        }
        
        // Create the barcode
        generateBarcode(upcNumber, humanReadableText);
        
    } catch (error) {
        alert("Error creating barcode: " + error.message);
    }
}

function calculateCheckDigit(digits) {
    var sum = 0;
    for (var i = 0; i < 11; i++) {
        var digit = parseInt(digits.charAt(i));
        if (i % 2 === 0) {
            sum += digit * 3; // Odd positions (1st, 3rd, 5th, etc.) multiply by 3
        } else {
            sum += digit; // Even positions multiply by 1
        }
    }
    var checkDigit = (10 - (sum % 10)) % 10;
    return checkDigit;
}

function generateBarcode(upcNumber, humanReadableText) {
    // Barcode dimensions
    var barWidth = 2; // Width of each bar in points
    var normalBarHeight = 60; // Height of number bars
    var guardBarExtension = normalBarHeight * 0.15; // Guard bars extend 15% below
    var textHeight = 12; // Text size
    var upcTextOffset = normalBarHeight * 0.1; // UPC text 10% lower than number bars
    var humanTextOffset = 8; // Space between UPC text and human readable text
    
    // Create new document or use active document
    var doc = app.activeDocument;
    
    // Create group for the barcode
    var barcodeGroup = doc.groupItems.add();
    barcodeGroup.name = "UPC Barcode: " + upcNumber;
    
    // Generate barcode pattern
    var barcodePattern = createBarcodePattern(upcNumber);
    
    // Draw bars
    var currentX = 0;
    var guardPositions = getGuardPositions();
    
    for (var i = 0; i < barcodePattern.length; i++) {
        if (barcodePattern.charAt(i) === "1") {
            var isGuardBar = isInGuardPositions(i, guardPositions);
            var barHeight = isGuardBar ? normalBarHeight + guardBarExtension : normalBarHeight;
            // All bars start at the same Y position (0), guard bars extend downward
            var bar = doc.pathItems.rectangle(0, currentX, barWidth, barHeight);
            bar.filled = true;
            bar.fillColor = createBlackColor();
            bar.stroked = false;
            bar.move(barcodeGroup, ElementPlacement.INSIDE);
        }
        currentX += barWidth;
    }
    
    // Add UPC number text
    var totalWidth = barcodePattern.length * barWidth;
    var upcTextItem = doc.textFrames.add();
    upcTextItem.contents = formatUPCText(upcNumber);
    upcTextItem.textRange.characterAttributes.size = textHeight;
    
    // Try to use a monospace font, fallback to default if not available
    try {
        upcTextItem.textRange.characterAttributes.textFont = app.textFonts.getByName("Courier New");
    } catch (e) {
        try {
            upcTextItem.textRange.characterAttributes.textFont = app.textFonts.getByName("Myriad Pro");
        } catch (e2) {
            try {
                upcTextItem.textRange.characterAttributes.textFont = app.textFonts.getByName("Consolas");
            } catch (e3) {
                // Use the first available font as fallback
                if (app.textFonts.length > 0) {
                    upcTextItem.textRange.characterAttributes.textFont = app.textFonts[0];
                }
            }
        }
    }
    
    // Position UPC text centered below barcode, some% lower than number bars
    var upcTextWidth = upcTextItem.width;
    upcTextItem.position = [
        (totalWidth - upcTextWidth) / 4,
        -(normalBarHeight + upcTextOffset + textHeight)
    ];
    
    upcTextItem.move(barcodeGroup, ElementPlacement.INSIDE);
    
    // Add human readable text if provided
    if (humanReadableText && humanReadableText.length > 0) {
        var humanTextItem = doc.textFrames.add();
        humanTextItem.contents = humanReadableText;
        humanTextItem.textRange.characterAttributes.size = textHeight;
        
        // Use same font as UPC text
        try {
            humanTextItem.textRange.characterAttributes.textFont = upcTextItem.textRange.characterAttributes.textFont;
        } catch (e) {
            if (app.textFonts.length > 0) {
                humanTextItem.textRange.characterAttributes.textFont = app.textFonts[0];
            }
        }
        
        // Position human readable text centered below UPC text
        var humanTextWidth = humanTextItem.width;
        humanTextItem.position = [
            (totalWidth - humanTextWidth) / 2,
            -(normalBarHeight + upcTextOffset + textHeight + humanTextOffset + textHeight)
        ];
        
        humanTextItem.move(barcodeGroup, ElementPlacement.INSIDE);
    }
    
    // Position the entire barcode group
    barcodeGroup.position = [100, -100]; // Adjust as needed
    
    alert("UPC Barcode created successfully!");
}

function createBarcodePattern(upcNumber) {
    var pattern = "";
    
    // Start guard
    pattern += guardPatterns.start;
    
    // Left side (first 6 digits)
    for (var i = 0; i < 6; i++) {
        var digit = parseInt(upcNumber.charAt(i));
        pattern += leftPatterns[digit];
    }
    
    // Middle guard
    pattern += guardPatterns.middle;
    
    // Right side (last 6 digits)
    for (var i = 6; i < 12; i++) {
        var digit = parseInt(upcNumber.charAt(i));
        pattern += rightPatterns[digit];
    }
    
    // End guard
    pattern += guardPatterns.end;
    
    return pattern;
}

function getGuardPositions() {
    // Returns array of bit positions where guard bars are located
    var positions = [];
    var pos = 0;
    
    // Start guard positions
    for (var i = 0; i < 3; i++) {
        if (guardPatterns.start.charAt(i) === "1") {
            positions.push(pos);
        }
        pos++;
    }
    
    // Skip left digits (6 * 7 bits)
    pos += 42;
    
    // Middle guard positions
    for (var i = 0; i < 5; i++) {
        if (guardPatterns.middle.charAt(i) === "1") {
            positions.push(pos);
        }
        pos++;
    }
    
    // Skip right digits (6 * 7 bits)
    pos += 42;
    
    // End guard positions
    for (var i = 0; i < 3; i++) {
        if (guardPatterns.end.charAt(i) === "1") {
            positions.push(pos);
        }
        pos++;
    }
    
    return positions;
}

function formatUPCText(upcNumber) {
    // Format as: 1 23456 78901 2 (first digit, space space, 5 digits, space space, 5 digits, space space, last digit)
    return upcNumber.charAt(0) + "  " + 
           upcNumber.substring(1, 6) + "  " + 
           upcNumber.substring(6, 11) + "  " + 
           upcNumber.charAt(11);
}

function isInGuardPositions(position, guardPositions) {
    for (var i = 0; i < guardPositions.length; i++) {
        if (guardPositions[i] === position) {
            return true;
        }
    }
    return false;
}

function createBlackColor() {
    var color = new CMYKColor();
    color.cyan = 0;
    color.magenta = 0;
    color.yellow = 0;
    color.black = 100;
    return color;
}

// Run the script
createUPCBarcode();