📇 QR Code

Generate QR codes in Deno, as base64-encoded images, completely dependency-free and requires no binary.

This is a port of zenozeng/node-yaqrcode, which itself is a port of the QR code generator in the d-project.

⭐ Getting started

import { qrcode } from "https://raw.githubusercontent.com/denorg/qrcode/da60b2680b4b56da03c635260e19f24f2fd0a44d/mod.ts";
const base64Image = await qrcode("bitcoin:ADDRESS?amount=0.5&label=ORDER"); // data:image/gif;base64,...

The deno.land/x/qrcode tag is still at v2.0.0 and does not include the current return type fix (#7). The source-revision URL above is pinned so the example type-checks without claiming a release that has not happened.

You can also add a custom size by specifying size in the second parameter:

const fixedSizeImage = await qrcode("bitcoin:ADDRESS?amount=0.5&label=ORDER", { size: 500 });

Return value

qrcode is asynchronous. It returns a Promise<string> that resolves to a complete GIF data URL (data:image/gif;base64,...), not a QR code object. You can use that string directly as an image source:

const imageSource: string = await qrcode("Hello world");
const html = `<img src="${imageSource}" alt="QR code">`;

To save the generated QR code as a GIF in Deno, decode the data URL first:

const dataUrl = await qrcode("Hello world");
const base64 = dataUrl.replace(/^data:image\/gif;base64,/, "");
const bytes = Uint8Array.from(
  atob(base64),
  (character) => character.charCodeAt(0),
);
await Deno.writeFile("qrcode.gif", bytes);

The generator only produces GIF data URLs; there is no option to request PNG output. If you need a PNG, decode the GIF and convert its first frame with an image library (this optional dependency is not needed to generate QR codes):

import { GIF } from "jsr:@matmen/imagescript@1.3.1";
import { qrcode } from "https://raw.githubusercontent.com/denorg/qrcode/da60b2680b4b56da03c635260e19f24f2fd0a44d/mod.ts";

const dataUrl = await qrcode("Hello world", { size: 250 });
const base64 = dataUrl.slice("data:image/gif;base64,".length);
const gifBytes = Uint8Array.from(
  atob(base64),
  (character) => character.charCodeAt(0),
);
const gif = await GIF.decode(gifBytes, true);
await Deno.writeFile("qrcode.png", await gif[0].encode());

Save this as convert.ts and run it with deno run --allow-write --allow-net=jsr.io convert.ts. ImageScript loads its WebAssembly encoder from JSR at runtime, so it needs access to jsr.io even when its import is cached.

Deno.serve example

The examples/server.ts file exposes QR codes over HTTP using Deno.serve:

deno run --allow-net examples/server.ts

Then open a URL like this to receive a GIF response:

http://localhost:4000/?data=Hello%20World!&size=250&typeNumber=5&errorCorrection=L

Short query parameters are also supported for compact URLs: d, s, v, and e.

CLI with DPX

After installing DPX, you can directly use the CLI using the dpx command:

dpx qrcode <text>

CLI

Alternatively, you can use it directly from the CLI by using deno run:

deno run https://deno.land/x/qrcode/cli.ts <text>

You can also install it globally using the following:

deno install https://deno.land/x/qrcode/cli.ts

Then, the package is available to run:

qrcode <text>

👩‍💻 Development

Run tests:

deno test

Notes

• To support typeNumber 40, use the RS_BLOCK_TABLE from davidshimjs/qrcodejs
• To support UTF-8, use the code from davidshimjs/qrcodejs
• Returns a base64-encoded image URL

⭐ Related Work

• zenozeng/node-yaqrcode is the Node.js project that is the origin of this implementation

📄 License

• MIT © Denorg
• Original repo: MIT © Zeno Zeng
• "QR Code" is registered trademark of Denso Wave

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