Client-Side QR Code Scanning Libraries for Web Applications
@zxing/library, html5-qrcode, jsqr, qr-scanner, and qrcode-reader are JavaScript libraries that enable QR code detection and decoding directly in the browser using device cameras or image inputs. These packages vary significantly in scope, API design, performance characteristics, and maintenance status. While some provide full-featured camera integration with real-time scanning, others focus solely on decoding raw pixel data from images or video frames, requiring developers to handle media setup manually.
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Client-Side QR Code Scanning: A Practical Comparison of JavaScript Libraries
When you need to scan QR codes in a web app, you have several libraries to choose from β but they differ dramatically in what they do, how much work they save you, and whether theyβre still maintained. Letβs cut through the noise and compare the real engineering trade-offs.
π« Deprecation Warning: Avoid qrcode-reader
First, the easy decision: qrcode-reader is deprecated. Its npm page states itβs no longer maintained, and the GitHub repo hasnβt seen updates in years. Donβt use it in new projects. Weβll include it in comparisons only for completeness, but treat it as obsolete.
πΈ Camera Integration vs Pure Decoding
The biggest split among these libraries is whether they handle the entire scanning flow (camera access, UI, real-time decoding) or just the decoding step (turning pixel data into text).
Full-Stack Scanners: html5-qrcode and qr-scanner
These packages manage everything:
- Request camera permissions
- Render a video feed
- Continuously analyze frames
- Fire callbacks when a QR code is found
html5-qrcode example:
import { Html5Qrcode } from "html5-qrcode";
const html5QrCode = new Html5Qrcode("reader");
html5QrCode.start(
{ facingMode: "environment" },
{ fps: 10, qrbox: { width: 250, height: 250 } },
(decodedText) => console.log("Found:", decodedText),
(errorMessage) => console.log("Error:", errorMessage)
);
qr-scanner example:
import QrScanner from "qr-scanner";
import QrFrame from "qr-scanner/qr-scanner.min.js";
const video = document.getElementById("video");
const scanner = new QrScanner(video, result => console.log(result));
scanner.start();
Note:
qr-scannerrequires you to include its worker script separately for optimal performance.
Decoder-Only Libraries: @zxing/library and jsqr
These expect you to provide raw image data (e.g., from a <canvas> or <video> frame). You handle camera setup, frame capture, and retry logic.
jsqr example:
import jsQR from "jsqr";
const canvas = document.createElement("canvas");
const ctx = canvas.getContext("2d");
// Assume video is already streaming
ctx.drawImage(video, 0, 0, canvas.width, canvas.height);
const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
const code = jsQR(imageData.data, imageData.width, imageData.height);
if (code) console.log("Found:", code.data);
@zxing/library example:
import { BrowserMultiFormatReader } from "@zxing/library";
const codeReader = new BrowserMultiFormatReader();
const video = document.querySelector("video");
// Start decoding from video stream
const controls = await codeReader.decodeFromVideoDevice(
null,
video,
(result, error, controls) => {
if (result) console.log("Found:", result.getText());
}
);
@zxing/librarydoes offer high-level camera helpers (decodeFromVideoDevice), but theyβre less polished thanhtml5-qrcodeβs API.
βοΈ Performance Considerations
jsqrruns entirely in the main thread. For smooth UI, you must throttle frame analysis (e.g., usingrequestAnimationFramewith skips).qr-scanneruses a Web Worker by default to avoid blocking the UI β a big plus for responsive apps.@zxing/librarycan be heavy because it supports many barcode formats; QR-only decoding is possible but not the default.html5-qrcoderuns decoding on the main thread but lets you limit FPS to reduce load.
π§ Customization and Control
Need to tweak the scanning region, add overlays, or handle multiple concurrent scans?
jsqrgives maximum control β you decide exactly which pixels to analyze and when.qr-scannerallows customizing the scan region and includes a built-in highlight box.html5-qrcodelets you configure the scan area (qrbox) but offers less visual customization.@zxing/libraryrequires manual DOM manipulation for overlays but supports advanced decoding hints.
π± Mobile and Permission Handling
All camera-enabled libraries must handle getUserMedia() permissions, but their approaches differ:
html5-qrcodeincludes built-in error messages for common issues (e.g., camera not found).qr-scannerthrows clear errors but leaves UI feedback to you.@zxing/librarypropagates rawDOMExceptions β youβll need to map them to user-friendly messages.
π§ͺ File and Image Support
What if you want to scan from an uploaded image, not a camera?
html5-qrcode:
Html5Qrcode.scanFile(file).then(text => console.log(text));
qr-scanner:
QrScanner.scanImage(fileOrUrl).then(result => console.log(result));
jsqr and @zxing/library require you to draw the image to a canvas first, then extract pixel data β more code, but more flexible.
π οΈ Error Handling Patterns
html5-qrcodeuses separate success/error callbacks.qr-scannerreturns promises that reject on errors.jsqrreturnsnullon failure β no exceptions thrown.@zxing/librarythrows errors during decoding, which you must catch in your callback.
π Summary Table
| Library | Camera Built-in? | Worker Support? | File Scanning? | Multi-Format? | Actively Maintained? |
|---|---|---|---|---|---|
@zxing/library | Partial | β | Manual | β | β |
html5-qrcode | β | β | β | QR only | β |
jsqr | β | β | Manual | QR only | β |
qr-scanner | β | β | β | QR only | β |
qrcode-reader | β | β | Manual | QR only | β (Deprecated) |
π‘ When to Use Which
- Building a simple QR scanner fast? β
html5-qrcode. Itβs the quickest path to a working demo. - Need smooth performance on mobile? β
qr-scannerwith its worker-based decoding. - Building a custom AR or multi-code experience? β
jsqrfor pixel-level control. - Scanning barcodes and QR codes in inventory apps? β
@zxing/library. - Starting a new project? β Never
qrcode-reader.
Choose based on whether you value convenience (html5-qrcode, qr-scanner) or control (jsqr, @zxing/library). And always check the official docs β APIs evolve, and assumptions can break.
How to Choose: @zxing/library vs html5-qrcode vs jsqr vs qr-scanner vs qrcode-reader
- @zxing/library:
Choose
@zxing/libraryif you need a mature, multi-format barcode/QR scanning solution that supports not just QR codes but also many 1D and 2D barcode formats. It provides both low-level decoding APIs and higher-level continuous scanning capabilities, though it requires more manual setup for camera handling compared to turnkey solutions. Best suited for applications requiring broad symbology support beyond QR codes. - html5-qrcode:
Choose
html5-qrcodeif you want a simple, all-in-one solution for real-time QR scanning from a webcam with minimal setup. It handles camera enumeration, permission requests, UI rendering, and decoding out of the box, making it ideal for quick integrations where developer experience and ease of use are prioritized over fine-grained control. - jsqr:
Choose
jsqrif you're building a custom scanning pipeline and only need a lightweight, dependency-free decoder for static images or pre-captured video frames. It gives you complete control over the media input and processing loop but requires you to implement camera access, frame extraction, and scanning logic yourself. Perfect for performance-critical or highly customized scanning scenarios. - qr-scanner:
Choose
qr-scannerif you need a balance between ease of use and performance, with built-in camera support and optional worker-based decoding for better responsiveness. It offers a clean API for both file and camera scanning, includes a highlight overlay for detected codes, and allows disabling worker usage if needed. A solid middle-ground choice for most web apps. - qrcode-reader:
Do not choose
qrcode-readerfor new projects β it is officially deprecated according to its npm page and GitHub repository. The package has not been updated in years and lacks modern features like camera integration or performance optimizations. Use one of the actively maintained alternatives instead.
Popular Comparisons
README for @zxing/library
ZXing
Project in Maintenance Mode Only
The project is in maintenance mode, meaning, changes are driven by contributed patches. Only bug fixes and minor enhancements will be considered. The Barcode Scanner app can no longer be published, so it's unlikely any changes will be accepted for it. There is otherwise no active development or roadmap for this project. It is "DIY".
Runs on your favorite ECMAScript ecosystem
If it doesn't, we gonna make it.
What is ZXing?
ZXing ("zebra crossing") is an open-source, multi-format 1D/2D barcode image processing library implemented in Java, with ports to other languages.
Supported Formats
See Projects and Milestones for what is currently done and what's planned next. π
| 1D product | 1D industrial | 2D |
|---|---|---|
| UPC-A | Code 39 | QR Code |
| UPC-E | Code 93 | Data Matrix |
| EAN-8 | Code 128 | Aztec |
| EAN-13 | Codabar | PDF 417 |
| ITF | ||
| RSS-14 | ||
| RSS-Expanded (not production ready!) |
Status
Attention
NOTE: While we do not have the time to actively maintain zxing-js anymore, we are open to new maintainers taking the lead.
Demo
See Live Preview in browser.
Note: All the examples are using ES6, be sure is supported in your browser or modify as needed, Chrome recommended.
Installation
npm i @zxing/library --save
or
yarn add @zxing/library
Limitations
On iOS-Devices with iOS < 14.3 camera access works only in native Safari and not in other Browsers (Chrome,...) or Apps that use an UIWebView or WKWebView. This is not a restriction of this library but of the limited WebRTC support by Apple. The behavior might change in iOS 11.3 (Apr 2018?, not tested) as stated here
iOS 14.3 (released in december 2020) now supports WebRTC in 3rd party browsers as well π
Browser Support
The browser layer is using the MediaDevices web API which is not supported by older browsers.
You can use external polyfills like WebRTC adapter to increase browser compatibility.
Also, note that the library is using the TypedArray (Int32Array, Uint8ClampedArray, etc.) which are not available in older browsers (e.g. Android 4 default browser).
You can use core-js to add support to these browsers.
In the PDF 417 decoder recent addition, the library now makes use of the new BigInt type, which is not supported by all browsers as well. There's no way to polyfill that and ponyfill libraries are way to big, but even if PDF 417 decoding relies on BigInt the rest of the library shall work ok in browsers that doesn't support it.
There's no polyfills for BigInt in the way it's coded in here.
Usage
// use with commonJS
const { MultiFormatReader, BarcodeFormat } = require('@zxing/library');
// or with ES6 modules
import { MultiFormatReader, BarcodeFormat } from '@zxing/library';
const hints = new Map();
const formats = [BarcodeFormat.QR_CODE, BarcodeFormat.DATA_MATRIX/*, ...*/];
hints.set(DecodeHintType.POSSIBLE_FORMATS, formats);
const reader = new MultiFormatReader();
const luminanceSource = new RGBLuminanceSource(imgByteArray, imgWidth, imgHeight);
const binaryBitmap = new BinaryBitmap(new HybridBinarizer(luminanceSource));
reader.decode(binaryBitmap, hints);
Contributing
See Contributing Guide for information regarding porting approach and reasoning behind some of the approaches taken.
Contributors
Special thanks to all the contributors who have contributed for this project. We heartly thankful to you all.
And a special thanks to @aleris who created the project itself and made available the initial QR code port.
