Generate QR codes with a REST API: one POST, instant SVG

Your e-commerce checkout needs to display a QR code for each order's tracking URL. You could install a client-side QR library, configure a canvas element, handle the rendering lifecycle, and add 30-40 KB to your bundle. Or you could send one POST request and get back an SVG.

The botoi /v1/qr/generate endpoint turns any string or URL into a scannable QR code. It returns raw SVG you can embed in HTML, save to a file, or stream to a PDF. No npm package, no canvas dependency, no build step.

The API call

Send a POST request with the text you want to encode:

curl -X POST https://api.botoi.com/v1/qr/generate \
  -H "Content-Type: application/json" \
  -d '{
    "text": "https://example.com/order/12345",
    "size": 300
  }'

The response is a raw SVG image (Content-Type: image/svg+xml):

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 37 37"
  shape-rendering="crispEdges">
  <path fill="#ffffff" d="M0 0h37v37H0z"/>
  <path fill="#000000" d="M4 4h7v1H4z ... "/>
</svg>

That SVG renders sharp at any size because it's vector-based. Drop it into an <img> tag, inline it in your HTML, or pipe it to a file. No JSON parsing needed; the response body is the SVG itself.

Parameters

The endpoint accepts six parameters. Only text is required:

• text (string, required): The URL or text to encode. Supports up to ~4,296 alphanumeric characters.
• size (number, default 300): Width and height in pixels. Range: 50 to 2000.
• darkColor (hex string, default #000000): Foreground color of the QR modules.
• lightColor (hex string, default #ffffff): Background color.
• errorCorrectionLevel (string, default M): One of L (7%), M (15%), Q (25%), or H (30%). Higher levels tolerate more damage but produce denser codes.
• margin (number, default 4): Quiet zone around the QR code in modules. Range: 0 to 20.

Here's a request using all six parameters:

curl -X POST https://api.botoi.com/v1/qr/generate \
  -H "Content-Type: application/json" \
  -d '{
    "text": "https://example.com/order/12345",
    "size": 400,
    "darkColor": "#1a1a2e",
    "lightColor": "#ffffff",
    "errorCorrectionLevel": "H",
    "margin": 2
  }'

Practical examples

Restaurant menu QR code

Print a QR code on table tents so diners can pull up the full menu on their phone. Error correction H handles scuffs and coffee stains.

curl -X POST https://api.botoi.com/v1/qr/generate \
  -H "Content-Type: application/json" \
  -d '{
    "text": "https://thecornergrille.com/menu",
    "size": 400,
    "errorCorrectionLevel": "H",
    "margin": 3
  }' --output menu-qr.svg

Event ticket QR code

Encode a unique ticket ID in each QR code. Staff scan it at the door with any smartphone camera. Error correction Q provides a good balance between density and damage tolerance for printed badges.

curl -X POST https://api.botoi.com/v1/qr/generate \
  -H "Content-Type: application/json" \
  -d '{
    "text": "https://tickets.devconf.io/check-in/TKT-8291-XKCD",
    "size": 250,
    "errorCorrectionLevel": "Q"
  }' --output ticket-8291.svg

Payment link QR code

Generate a scannable payment link for invoices, receipts, or point-of-sale displays. The customer scans it and lands on a Stripe checkout page.

curl -X POST https://api.botoi.com/v1/qr/generate \
  -H "Content-Type: application/json" \
  -d '{
    "text": "https://pay.stripe.com/b/live_abc123def456",
    "size": 300,
    "errorCorrectionLevel": "M"
  }' --output payment-qr.svg

Batch generation in a loop

Need QR codes for a product catalog? Loop through a list of URLs and save each SVG to disk. This bash script generates four QR codes in under a second:

#!/bin/bash
set -euo pipefail

URLS=(
  "https://shop.example.com/product/wireless-earbuds"
  "https://shop.example.com/product/usb-c-hub"
  "https://shop.example.com/product/mechanical-keyboard"
  "https://shop.example.com/product/webcam-1080p"
)

mkdir -p qr-codes

for URL in "${URLS[@]}"; do
  SLUG=$(echo "$URL" | sed 's|.*/||')
  curl -s -X POST https://api.botoi.com/v1/qr/generate \
    -H "Content-Type: application/json" \
    -d "{
      \"text\": \"$URL\",
      \"size\": 400,
      \"errorCorrectionLevel\": \"M\"
    }" > "qr-codes/$SLUG.svg"

  echo "Generated: qr-codes/$SLUG.svg"
done

echo "Done. $(ls qr-codes/*.svg | wc -l) QR codes generated."

Output:

Generated: qr-codes/wireless-earbuds.svg
Generated: qr-codes/usb-c-hub.svg
Generated: qr-codes/mechanical-keyboard.svg
Generated: qr-codes/webcam-1080p.svg
Done. 4 QR codes generated.

Node.js example: QR codes for order tracking

This Express server exposes a /orders/:id/qr endpoint. When your checkout page or confirmation email template fetches this URL, it gets back an SVG QR code pointing to the order's tracking page.

import express from "express";

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

app.get("/orders/:id/qr", async (req, res) => {
  const trackingUrl = `https://track.mystore.com/orders/${req.params.id}`;

  const qrResponse = await fetch("https://api.botoi.com/v1/qr/generate", {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "Authorization": "Bearer YOUR_API_KEY",
    },
    body: JSON.stringify({
      text: trackingUrl,
      size: 300,
      errorCorrectionLevel: "M",
    }),
  });

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

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

Usage:

# Returns an SVG QR code for order ORD-5482
curl http://localhost:3000/orders/ORD-5482/qr --output order-qr.svg

The endpoint sets a 24-hour cache header so repeat requests for the same order don't hit the API again. In production, add Redis or a CDN in front of this route for higher traffic.

Client-side QR libraries vs API: when to use which

Feature                  | QR code API                | Client-side library (qrcode.js)
─────────────────────────|────────────────────────────|────────────────────────────────
Setup                    | 0 dependencies             | npm install + bundler config
Bundle size impact       | 0 KB                       | 25-45 KB (gzipped)
Server-side rendering    | Yes (returns SVG string)    | No (needs DOM or canvas)
Custom colors            | darkColor / lightColor      | Varies by library
Error correction         | L, M, Q, H                 | Depends on library
Batch generation         | Shell script or server loop | Needs Node.js + canvas
Print-ready SVG          | Default output              | Extra config or library
Offline support          | No (needs network)          | Yes (runs in browser)
Latency                  | ~50-100ms network round trip| ~5ms local render

Use the API when you need server-side generation (emails, PDFs, receipts), when you want to keep your frontend bundle small, or when you're generating QR codes in a backend workflow like order processing or ticket issuance.

Use a client-side library when your app needs to work offline, when latency matters more than bundle size (sub-5ms renders), or when you're building a tool where users generate QR codes interactively in the browser and you don't want to depend on a network request for each keystroke.

Key points

- POST /v1/qr/generate returns an SVG QR code from any text or URL
- Six parameters: text, size, darkColor, lightColor, errorCorrectionLevel, margin
- Response is raw SVG (image/svg+xml), not JSON-wrapped; embed it directly in HTML
- Free tier: 5 requests per minute, no API key needed
- Use error correction level H when printing or overlaying logos
- The API also accepts GET requests with query parameters for quick browser testing

The free tier at 5 requests per minute covers development, prototyping, and low-volume production use. For batch generation or high-traffic apps, add your API key in the Authorization: Bearer header. Check the API docs for the full endpoint reference.