Elchin Abdullayev
QRolling Engineering | Backend & Analytics
Elchin Abdullayev works on QRolling's backend and analytics layer. He writes about the technical side of QR codes — scan tracking, data pipelines, integrations — and the operational lessons from running production infrastructure for a small SaaS.
Articles by Elchin Abdullayev
QR Code Security: What You Need to Know
Essential security tips and best practices for protecting your QR codes from malicious use.
4 min read
Creating Dynamic QR Codes for Better Analytics
Understand the benefits of dynamic QR codes and how to track their performance effectively.
6 min read
Understanding QR Code Metrics: What Your Scan Data Really Says
Learn how to interpret scan data and optimize your QR code performance.
9 min read
QR Codes vs NFC: Which Technology is Right for Your Business?
QR codes and NFC compared on cost, security, durability, and user experience, plus the cases where running both makes sense.
7 min read
Integrating QR Codes with Your CRM System
Learn how to connect QR code campaigns with your customer relationship management for better insights.
7 min read
QR Code Accessibility: Making Your Codes Work for Everyone
Guidelines for creating QR code experiences that are accessible to people with disabilities.
7 min read
How Do QR Codes Work? From Black Squares to a Web Page
A plain-English walkthrough of what the corner squares do, how the grid stores bits, why damaged codes still scan, and what happens after your camera reads one.
6 min read
How to See a QR Code's Link Before You Tap It
Decode a QR code without opening it, read the real domain in a camera preview, and spot the red flags on payment and login codes before you act.
6 min read
Do QR Codes Work Without Internet?
Scanning never needs a connection because decoding happens on the device. What happens next depends entirely on what the code actually contains.
5 min read
What Happens When You Scan a QR Code
Decoding happens on your phone and sends nothing anywhere. Here is what a site sees after you tap, what dynamic codes log, and what nobody ever sees.
6 min read
Are QR Codes Free to Use? Patents, Trademarks and Costs
Denso Wave holds QR patent rights and chose not to enforce them, and the spec is an ISO standard. What the trademark limits, and what actually costs money.
6 min read
How Much Data Can a QR Code Hold?
The maximums are 7,089 numeric characters and 2,953 bytes, but error correction and print size cap you long before the spec ever does. Here is the math.
5 min read
How Many QR Codes Are Possible?
Version 40 holds 2,953 bytes, so the byte-mode bound is a number with 7,112 digits. What each of the three possible counts actually measures, and the one limit a real system hits.
6 min read
QR Error Correction Levels: When to Use L, M, Q or H
L, M, Q and H recover about 7%, 15%, 25% and 30% of codewords. What that really means, what it costs in capacity, and how to pick the right level.
6 min read
QR Code Versions 1-40: Module Counts and What Changes
Version 1 is 21x21 modules and version 40 is 177x177. What grows with the version, what never moves, and why a QR code densifies without warning.
5 min read
Why Your QR Code Looks Too Dense
A dense code is a long string, not a rendering choice. What a tracking URL costs in modules, why level H adds more, and the 0.4mm floor that decides whether it prints.
6 min read
Deep Links vs Universal Links Behind a QR Code
Custom schemes fail silently when an app is missing. Universal Links and App Links degrade to the web. Which one belongs behind a printed QR code.
6 min read
Inside a QR Code: Finder, Alignment and Timing Patterns
The three corner squares, the smaller alignment blocks and the dotted timing lines each do one job. What they are and why every decoder needs them.
6 min read
QR Mask Patterns: The 8 Rules That Keep Codes Readable
Encoders XOR the data region against eight fixed patterns, score each with four penalty rules, and keep the best. Why identical data gives different codes.
6 min read
Micro QR and rMQR: Smaller Codes and Their Real Limits
Micro QR uses one finder pattern and a two-module margin. rMQR is rectangular. Both trade capacity for size, and reader support is the deciding constraint.
6 min read
Round QR Codes Are Square Codes Wearing a Circle
A circular QR code is a standard square symbol inside a ring, and the ring is what fails. Where the margin dies on the diagonals, and why a genuinely rectangular code is a different symbology.
7 min read
QR vs Data Matrix vs PDF417 vs Aztec: Picking a Symbology
Data Matrix for tiny parts, PDF417 for licenses and boarding passes, Aztec for transit tickets, QR for anything a phone reads. Choosing by scanning environment.
6 min read
How QR Scanners Decode: Reed-Solomon in Plain English
Binarization, finder patterns, perspective correction, masking, and the error correction that rebuilds missing codewords, explained without the algebra.
6 min read
Dynamic QR Redirects: 301 vs 302 and What It Does to Your Data
A dynamic QR code is a redirect. Returning 301 instead of 302 quietly deletes scans from your reports and can strand phones on an old destination.
5 min read
QR Codes and Non-Latin Text: UTF-8, ECI and Kanji Mode
Cyrillic, Arabic, Turkish and CJK text can decode as mojibake. How byte mode, ECI designators and Kanji mode work, and how to keep text readable.
5 min read
Warehouse QR Labels for Bins, Pallets and Cycle Counts
How to build a warehouse label scheme for bins, pallets and cycle counts that scans fast, survives the floor, and still stays readable to humans.
7 min read
Machine-Level QR Codes for Maintenance Logs and SOPs
A practical plan for putting one QR code on every machine: SOPs, service history, fault reporting, and what to do when the plant floor has no signal.
7 min read
What Is an eSIM QR Code and How Do You Scan It?
Your carrier sent a square image to activate a mobile plan. Here is what it actually contains, where to scan it, and why doing it on WiFi first matters.
7 min read
QR Code Login: How Scanning Signs You In
Scan a square on a TV screen and you are logged in seconds later. Here is the handshake behind it, why the code expires fast, and the rule that keeps it safe.
6 min read
The QR Code in Your Authenticator App, Explained
That setup square is a shared secret in disguise. What it stores, why a screenshot of it is as dangerous as a password, and how to move it to a new phone.
7 min read
Pairing a Device by Scanning a QR Code
A pairing code is a ticket, not a password. What the code carries in each of the three pairing shapes, why it has to expire, and the failures that follow a screenshot.
6 min read
How to Blur or Hide a QR Code in a Photo
A light blur or a small emoji will not hide a QR code from a decoder. Here is what actually removes one from a screenshot before you post the image anywhere.
6 min read
What You Are Actually Scanning When You Scan an Apple Pay QR Code
Apple Pay is NFC and has no QR payload. The three things people are really scanning, how iOS routes a payment URL to an app, and what a business should print instead.
7 min read
GiroCode and the EPC Payment QR Format
What a GiroCode holds, the EPC069-12 line order, which banking apps read it, and why an IBAN printed into a symbol can never be corrected afterwards.
6 min read
Where Your QR Code Scan History Actually Lives
Camera apps decode and forget, so the trail is your browser history or your Google account activity. Code owners get counts only when the code routes through a redirect they control.
7 min read
Adding QR Code Login to Your Own App
Build scan-to-sign-in yourself: the pending session, the approval handshake, expiry and binding rules, and the phishing risk that defines the pattern.
6 min read
Why a QR Code Scans on iPhone but Not on Android
One phone opens the link before you finish raising it, the other sits there doing nothing. What differs between platforms, and the order to test it in.
5 min read
CSV Workflows for QR Codes: Import, Map, Verify
Design the sheet, dodge the encoding traps that corrupt URLs, validate destinations before generation, and decode a sample before anything reaches print.
6 min read
Automating QR Code Creation With APIs and Automation Tools
Generate codes automatically from orders, assets, or signups: API anatomy, idempotent webhooks, rate limits, and no-code paths for teams without engineers.
6 min read
Scan Tracking and Privacy: Consent, IPs, and Retention
What scan logs collect, why an IP address complicates things, where a consent banner cannot reach, and how to set retention. General info, not legal advice.
6 min read
QR Code vs Barcode: Which One Does Your Product Need?
Linear barcodes run retail checkout. QR codes carry more and any phone reads them. How to pick per use case, and why point of sale is moving to 2D.
6 min read
Choosing a QR Code API: What to Compare
A QR API can mean a stateless image endpoint or a managed redirect service. Compare formats, batching, auth, storage, idempotency, uptime and licensing.
6 min read
QR Code Generator vs URL Shortener: When to Use Each
A shortener makes text; a QR generator makes a scannable pattern. Where they overlap, how link rot differs, and why clicks and scans measure different people.
6 min read
WiFi QR Codes for Offices and Guest Networks
A lobby WiFi code is a physical asset anyone can photograph. How to scope it to guest-only, place it, and rotate the password without a full reprint.
6 min read
WiFi QR Code Scans but Won't Connect
The camera reads the code and nothing happens. Nine WiFi-specific reasons a scan fails to join a network, and the order worth checking them in.
6 min read
Hidden SSIDs and WPA3: WiFi QR Code Edge Cases
Why some WiFi codes join instantly and others fail: hidden network flags, security type mismatches, escaped punctuation, odd SSIDs, and enterprise logins.
6 min read
Is It Safe to Put Your WiFi Password in a QR Code?
A WiFi code holds your password in readable form, so the real question is who can see the card. Guest networks, rotation, and the photo mistake people make.
6 min read
QR Codes for Photographers, From Album Cards to Client Galleries
Album cards sit in a box for decades while the gallery behind them archives in months, so the destination has to stay editable. Also print backs, guest uploads, and links that are keys.
6 min read
One Code Per Item: Serializing QR Codes Properly
Where the serial lives, why the printed string can never change afterwards, what a UUID costs you in module width, and which check digit catches a transposition.
7 min read
Funny QR Codes People Actually Scan, and the Habit That Keeps It Safe
Shirt patches, one-line joke pages and voice-note gift tags, plus why latte-art codes scan about one time in ten. Then the two-second check that catches a sticker over a real code.
6 min read
QR Code Stencils and Spray Paint: Solving the Island Problem
A stencil cannot hold a light area with dark on all sides, and a QR code is full of them. What bridges do to a symbol, why the finder patterns are the hard part, and the size where it starts to work.
6 min read
The World's Largest QR Codes and What Breaks at That Scale
Hillsides, snowfields, rooftops and crop fields obey the same sizing ratio as a business card. The failure modes that only appear at architectural scale: altitude, reflectance, and a margin made of land.
8 min read
Using a QR Code as a Lock Screen or Desktop Wallpaper
A wallpaper code is for other people's phones, never your own. The guest wifi screen, the contact code for a lost phone, where the clock lands, and the resolution to build at.
7 min read
Inverted QR Codes: Light Modules on a Dark Background
The format specifies dark on light, and the finder search looks for dark runs first. Which readers try the inverted pass, which refuse outright, and what to do instead.
7 min read
France's AGEC Product Sheet: Where the QR Code Fits
France's AGEC product sheet on environmental qualities must sit on a web page for each model. No QR code is required, but it is how shoppers reach it in store.
6 min read
Carte Vitale App: How the QR Code Works at the Doctor's
How the carte Vitale app's QR code works at a doctor or pharmacy: activation routes, what the scan triggers, why QR beats NFC, and who accepts it in 2026.
5 min read
