Technical Security & Privacy Architecture
How QRCodeTechy generates ISO 18004-compliant QR codes entirely in your browser — and why your data never leaves your device.
Browser-Side Architecture: No Server Uploads
Most online tools process your data on their servers — your WiFi password, UPI ID, or contact details travel over the internet to a remote machine before a QR code is returned. QRCodeTechy takes a fundamentally different approach: all QR generation logic runs inside your browser's JavaScript engine.
When you enter data in the generator, it flows through these local steps:
- Input Parsing: Your text/URL/contact data is read by the JavaScript input handler.
- Data Encoding: The QR library determines the optimal encoding mode — Numeric, Alphanumeric, Byte, or Kanji — based on your content to minimize QR code size.
- Error Correction Calculation: Reed-Solomon error correction codewords are computed locally. The level (L, M, Q, or H) is selected based on your settings and whether a logo is embedded.
- Matrix Construction: The 2D module grid (the dark/light squares) is built entirely in memory.
- SVG/PNG Rendering: The canvas or SVG is drawn in the browser. The download is a direct browser-to-disk save — no upload occurs.
You can verify this yourself: open your browser's developer tools (F12) → Network tab → generate a QR code → observe that no POST or GET request containing your input data is made to any external endpoint. The only network activity is loading the page's static assets on first visit.
The QR Code Standard: ISO/IEC 18004:2015
QR codes are not a proprietary format — they are governed by an international standard: ISO/IEC 18004:2015 (Information technology — Automatic identification and data capture techniques — QR Code bar code symbology specification). This standard, originally developed by Denso Wave in 1994, defines every aspect of a valid QR code.
Versions (Size)
QR codes range from Version 1 (21×21 modules) to Version 40 (177×177 modules). Each version can store more data. The generator automatically selects the smallest version that fits your content, producing the simplest possible QR for maximum scannability.
Encoding Modes
Numeric (digits only, 3.33 bits/char), Alphanumeric (A-Z, 0-9, symbols — 5.5 bits/char), Byte (full Latin-1/UTF-8 — 8 bits/char), Kanji (double-byte Japanese — 13 bits/char). Using Alphanumeric mode for uppercase URLs, or Numeric for phone numbers, produces smaller, faster-scanning QR codes than Byte mode.
Finder Patterns & Timing
The three square patterns in the corners (Finder Patterns) allow scanners to locate and orient the QR code at any rotation angle. Alignment Patterns (small squares in the interior of higher-version QR codes) correct for perspective distortion when the code is photographed at an angle.
Reed-Solomon Error Correction: The Mathematics of Resilience
Reed-Solomon (RS) error correction is the same technology used in CDs, DVDs, and deep-space communication. In QR codes, it adds redundant mathematical data that allows a reader to reconstruct the original message even if part of the code is damaged, dirty, or obscured by a logo.
ISO 18004 defines four error correction levels:
| Level | Name | Recovery Capacity | Best For |
|---|---|---|---|
| L | Low | ~7% of data modules | Clean environments, digital display |
| M | Medium | ~15% of data modules | General use, printed materials |
| Q | Quartile | ~25% of data modules | Industrial, outdoor signage |
| H | High | ~30% of data modules | Logo-embedded QR codes ✓ |
How RS Error Correction Works: The data codewords are treated as coefficients of a polynomial over a Galois Field GF(2⁸) (a finite field with 256 elements). RS encoding computes a remainder polynomial by dividing the data polynomial by a generator polynomial of degree 2t (where t is the number of correctable errors). This remainder — the RS codewords — is appended to the data. During decoding, the reader evaluates the received polynomial to detect and correct up to t symbol errors.
Why Level H for Logos: When a logo is embedded in the center of a QR code, it covers approximately 10–25% of the data modules. At Level H, the QR code can lose up to 30% of its modules and still decode correctly. Logos placed correctly stay within this safe zone. Using Level L or M with a logo would frequently cause scan failures — which is why our generator automatically upgrades to Level H when logo embedding is enabled.
Privacy Commitments
No server-side data processing
QR generation is 100% client-side JavaScript. Your WiFi password, UPI ID, contact details, and URLs never leave your browser.
No QR content logging
We do not store, analyze, or transmit the content of QR codes you create. No database of "what QR codes people generated" exists.
Static QR codes — no dynamic redirects
QRCodeTechy generates static QR codes that encode your destination directly. There is no intermediate redirect server that could go offline, change the destination, or track scans.
No registration required
We do not collect your email address, create user accounts, or require any personal information to use the generator.
No QR code expiration
Static QR codes never expire. Since we don't control a redirect server, there is no subscription or payment required to keep your QR codes working indefinitely.
Questions About Our Technology?
We welcome technical scrutiny. If you have questions about our implementation, security architecture, or QR standard compliance, contact us at qrcodetechy@calculatorsuites.com.