# Overview

The Weixin Unique Item Code feature gives each product a unique QR code that is integrated with Weixin's native capabilities. With this feature, brand owners can connect each product with consumers to provide product information and anti-counterfeit services, encouraging them to follow Official Accounts and send red packets for accurate target marketing and better user and data management.

How it works

Weixin QR codes consist of a fixed prefix, a translated and compressed product ID, and a custom parameter. The fixed prefix is a 16-character string for Weixin identification. The product ID is a unique 12-character string for product identification. The custom parameter is entered by a merchant and passed through as the primary key in the entire process: QR code is generated > user scans the QR code > user opens product page > user visits page set by the merchant. Merchants can receive events pushed by Weixin and check the ticket to find the relationship between a QR code and a user.

Backend interaction mode

QR code description

| Field | Description

Steps

Step1: Get merchant information

Step 2: Create product

Step 3: Publish product

Step 4: Get product QR code

Step 5: Print QR code

Recommended QR code version

QR Code rules

To better print the QR code, see rules at http://www.qrcode.com/zh/about/version.html.

The length of extinfo, QR code version, correction level, and QR code size may affect the QR code printing effect. For QR codes with the same content, those with a higher correction level have a higher version. For QR codes of the same version, those with a higher correction level contain less content.

QR code Version L2 and L3 are recommended on the Weixin platform. Version L4 can be used in extreme cases.

| QR Code Version | Number of Available Character Positions | Number of Occupied Positions

Note: A matrix of 25*25 means there are 25 data points per row and per column in a QR code.

Version image examples

Example 1: Different sizes of Version L2 QR code with extinfo parameter of no more than 4 characters and matrix of 25*25

The QR code content is http://p.url.cn/yA4AcHqlXqY/1234.

Example 2: Different sizes of Version L3 QR code with extinfo parameter of no more than 25 characters and matrix of 29*29

The QR code content is http://p.url.cn/yA4AcHqlXqY/0123456789012345678901234.

Example 3: Different sizes of Version L4 QR code with extinfo parameter of no more than 50 characters and matrix of 33*33

The QR code content is http://p.url.cn/yA4AcHqlXqY/01234567890123456789012345678901234567890123456789.