Barcode generator API: one POST, SVG output, six formats

Your warehouse app prints shipping labels. Each label needs a Code128 barcode for the tracking number. You could install a barcode library, render to canvas, export as PNG, and embed it in your label template. Or you could send one POST and get back an SVG.

The botoi /v1/barcode endpoint encodes data into six barcode formats and returns an SVG string inside a JSON response. No npm package. No build step. No canvas dependency.

The API call

Send a POST request with the data and format:

curl -X POST https://api.botoi.com/v1/barcode \
  -H "Content-Type: application/json" \
  -d '{
    "data": "5901234123457",
    "format": "ean-13"
  }'

The response wraps the SVG in a standard JSON envelope:

{
  "success": true,
  "data": {
    "svg": "<svg xmlns=\"http://www.w3.org/2000/svg\" width=\"200\" ...>...</svg>",
    "data": "5901234123457",
    "encoding": "ean-13"
  }
}

Extract the svg field, drop it into an <img> tag, inline it in HTML, or pipe it to a file. The SVG renders sharp at any size because it's vector-based; no rasterization artifacts at 300 DPI or higher.

Parameters

The endpoint accepts five parameters. Only data is required:

• data (string, required): The value to encode. For EAN-13, pass 13 digits. For Code128, pass any printable ASCII string.
• format (string, default code128): One of code128, ean-13, ean-8, upc-a, itf-14, or msi.
• width (number, default 200): Image width in pixels. Range: 50 to 2000.
• height (number, default 80): Image height in pixels. Range: 20 to 1000.
• show_text (boolean, default true): Whether to render the encoded value as text below the bars.

Here's a Code128 barcode with all parameters set:

curl -X POST https://api.botoi.com/v1/barcode \
  -H "Content-Type: application/json" \
  -d '{
    "data": "SHIP-2026-03-29-0042",
    "format": "code128",
    "width": 300,
    "height": 100,
    "show_text": true
  }'

Practical examples

Shipping label generation

Encode a tracking number as Code128 for packing slips and shipping labels. Code128 handles mixed alphanumeric strings, so tracking numbers like "1Z999AA10123456784" work without preprocessing.

curl -X POST https://api.botoi.com/v1/barcode \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "data": "1Z999AA10123456784",
    "format": "code128",
    "width": 400,
    "height": 80,
    "show_text": true
  }'

Inventory management system

Print Code128 labels for warehouse bins and shelves. Staff scan them with handheld readers during pick-and-pack. The barcode encodes the full location path: warehouse, shelf, bin.

curl -X POST https://api.botoi.com/v1/barcode \
  -H "Content-Type: application/json" \
  -d '{
    "data": "SKU-WH3-SHELF-09-BIN-44",
    "format": "code128",
    "width": 250,
    "height": 60,
    "show_text": true
  }'

Retail product labels (EAN-13)

EAN-13 is the international standard for retail products. Pass the 13-digit GTIN and the API returns an SVG sized for standard shelf-edge labels.

curl -X POST https://api.botoi.com/v1/barcode \
  -H "Content-Type: application/json" \
  -d '{
    "data": "5901234123457",
    "format": "ean-13",
    "width": 200,
    "height": 100,
    "show_text": true
  }'

Node.js batch generation for a product catalog

Generate barcodes for an entire product catalog in parallel. This script fires four requests concurrently and collects the SVG strings:

const products = [
  { sku: "4006381333931", name: "wireless-earbuds" },
  { sku: "5901234123457", name: "usb-c-hub" },
  { sku: "8710398527837", name: "mechanical-keyboard" },
  { sku: "3614272049529", name: "webcam-1080p" },
];

async function generateBarcodes() {
  const results = await Promise.all(
    products.map(async (product) => {
      const res = await fetch("https://api.botoi.com/v1/barcode", {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
          "Authorization": "Bearer YOUR_API_KEY",
        },
        body: JSON.stringify({
          data: product.sku,
          format: "ean-13",
          width: 200,
          height: 100,
          show_text: true,
        }),
      });

      const json = await res.json();
      return { name: product.name, svg: json.data.svg };
    })
  );

  console.log(`Generated ${results.length} barcodes`);
  return results;
}

generateBarcodes();

Output:

Generated 4 barcodes

For catalogs with hundreds of products, batch in groups of 20-50 to stay within rate limits. The free tier caps at 5 requests per minute; an API key removes that limit.

Node.js example: barcode labels for order fulfillment

This Express server exposes a /labels/:orderId endpoint. When your fulfillment system or label printer fetches this URL, it gets back an SVG barcode encoding the order's tracking number.

import express from "express";
import fs from "fs/promises";

const app = express();
app.use(express.json());

app.get("/labels/:orderId", async (req, res) => {
  const trackingNumber = `SHIP-${req.params.orderId}`;

  const barcodeRes = await fetch("https://api.botoi.com/v1/barcode", {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "Authorization": "Bearer YOUR_API_KEY",
    },
    body: JSON.stringify({
      data: trackingNumber,
      format: "code128",
      width: 400,
      height: 80,
      show_text: true,
    }),
  });

  const json = await barcodeRes.json();

  res.setHeader("Content-Type", "image/svg+xml");
  res.setHeader("Cache-Control", "public, max-age=86400");
  res.send(json.data.svg);
});

app.listen(3000, () => console.log("Label server running on port 3000"));

Usage:

# Returns an SVG barcode for order ORD-7291
curl http://localhost:3000/labels/ORD-7291 --output label.svg

The 24-hour cache header prevents duplicate API calls for the same order. In production, add a CDN or Redis cache in front of this route.

When to use which format

Format     | Characters          | Length    | Use case
-----------|---------------------|-----------|-------------------------------------------
Code128    | ASCII 32-126        | Variable  | Shipping labels, internal IDs, serial numbers
EAN-13     | Digits only         | 13        | Retail products (international standard)
EAN-8      | Digits only         | 8         | Small retail packages
UPC-A      | Digits only         | 12        | Retail products (US and Canada)
ITF-14     | Digits only         | 14        | Shipping cartons and outer packaging
MSI        | Digits only         | Variable  | Warehouse shelves and inventory bins

Code128 is the default for a reason: it encodes the widest range of characters and works for most internal systems. Switch to EAN-13 or UPC-A when your product needs a retail-scannable barcode. Use ITF-14 for outer carton labels in logistics. MSI fits warehouse shelf labeling where you need numeric-only codes with a simple check digit.

Key points

- POST /v1/barcode returns an SVG barcode inside a JSON response
- Supported formats: Code128, EAN-13, EAN-8, UPC-A, ITF-14, MSI
- Parameters: data, format, width, height, show_text
- Code128 handles letters, digits, and symbols; the rest are numeric only
- SVG output scales cleanly for both screen display and 300 DPI print
- Free tier: 5 requests per minute, no API key required

The free tier at 5 requests per minute covers development, testing, and low-volume label printing. For batch generation or high-traffic fulfillment systems, pass your API key in the Authorization: Bearer header. Check the API docs for the full endpoint reference.