Scan QR Code
Original Image
Detection
What Is a QR Code?
A QR code (Quick Response code) is a two-dimensional barcode that stores data in a grid of black and white squares. Unlike traditional barcodes that hold only a product number, QR codes can encode URLs, text, contact information, WiFi credentials, and more—up to 4,296 alphanumeric characters.
QR codes were invented in 1994 by Denso Wave for tracking automotive parts. Today they're used for payments, menus, tickets, authentication, and sharing links without typing.
Data Types This Scanner Detects
| Type | What It Contains | Example |
|---|---|---|
| URL | Website link | https://example.com/page |
| Text | Plain text message | Meeting at 3pm in Room 201 |
| vCard | Contact card with name, phone, email | BEGIN:VCARD... |
| WiFi | Network name (SSID) and password | WIFI:T:WPA;S:MyNetwork;P:password123;; |
| Email address (mailto link) | mailto:[email protected] | |
| Phone | Phone number (tel link) | tel:+1234567890 |
| SMS | Pre-filled text message | sms:+1234567890?body=Hello |
| Calendar | Event with date, time, location | BEGIN:VEVENT... |
| Geo | Geographic coordinates | geo:37.7749,-122.4194 |
How QR Code Scanning Works
- Image capture: The scanner receives an image containing a QR code (photo, screenshot, or camera feed).
- Pattern detection: Software locates the three position markers (large squares in corners) that define the QR code boundaries.
- Grid analysis: The scanner reads each cell in the grid as either black (1) or white (0) to extract the binary data.
- Error correction: QR codes include redundant data. The scanner can reconstruct missing or damaged portions—up to 30% of the code can be unreadable and still decode successfully.
- Decoding: The binary data is converted to text using the encoding mode specified in the QR code (numeric, alphanumeric, byte, or kanji).
Tips for Better Scanning
- Ensure full visibility: The entire QR code must be in frame, including the quiet zone (white border around the code).
- Good contrast: QR codes need clear distinction between dark and light modules. Avoid glare or shadows.
- Sufficient resolution: Each cell in the QR code should be at least 10 pixels across for reliable scanning.
- Flat surface: Scanning a QR code on a curved surface (like a bottle) may distort the pattern.
- Clean lens: If scanning with a camera, ensure the lens isn't smudged or scratched.
Privacy & Security
This scanner processes images entirely in your browser using JavaScript. Your images are never uploaded to any server. The decoding library (jsQR) runs locally on your device.
QR code safety tips:
- Always preview decoded URLs before clicking—phishing attacks use QR codes to hide malicious links.
- Be cautious with QR codes on stickers that may have been placed over legitimate codes.
- Public WiFi QR codes can direct you to fake networks. Verify the network name matches what you expect.
- QR codes for payments should only be scanned from trusted sources.
Frequently Asked Questions
How do I scan a QR code from a screenshot?
Upload the screenshot to this tool by clicking the upload area or dragging and dropping the image. The scanner analyzes the image pixels to locate and decode the QR pattern. This works with screenshots from phones, computers, or any saved image containing a QR code.
What data can a QR code contain?
QR codes can encode URLs, plain text, WiFi network credentials (SSID and password), contact cards (vCard), calendar events, email addresses, phone numbers, SMS messages, geographic coordinates, and cryptocurrency addresses.
Is it safe to scan unknown QR codes?
Use caution with unknown QR codes. They may link to phishing sites or malicious downloads. Always preview the decoded content before opening URLs. This scanner shows you the data first without automatically redirecting.
Why won't my QR code scan?
Common reasons: the image is blurry, the QR code is partially obscured, there's not enough contrast, or the QR code is damaged. Try a higher resolution image, ensure the entire code is visible, and check that lighting doesn't create glare.
What's the difference between QR codes and barcodes?
Barcodes are one-dimensional (lines) and hold limited data like product IDs. QR codes are two-dimensional (squares) and can store much more data—up to 4,296 alphanumeric characters. QR codes also have error correction, so they work even when partially damaged.
Can QR codes be scanned from any angle?
QR codes can be scanned at various angles because they contain position markers (the three large squares in corners) that help scanners orient the code. However, extreme angles or perspective distortion may cause scanning to fail.
How much data can a QR code hold?
A QR code can hold up to 7,089 numeric characters, 4,296 alphanumeric characters, or 2,953 bytes of binary data. In practice, most QR codes contain URLs or short text under 300 characters for reliable scanning.
Do QR code scanners store my images?
This scanner does not upload or store your images. The decoding happens entirely in your browser using JavaScript. Your images never leave your device.
Can I scan a QR code from a PDF?
Yes. Take a screenshot of the QR code in the PDF, or use your PDF viewer's snapshot tool to capture the QR code area, then upload that image to the scanner.
What if the QR code links to a suspicious website?
This scanner shows you the decoded content before you take any action. If a URL looks suspicious (misspellings, unusual domains, unexpected destinations), do not click the "Open URL" button. You can copy the text to inspect it further.
Can damaged QR codes still be scanned?
Yes, QR codes include error correction that allows them to be read even when partially damaged. Depending on the error correction level, up to 7%, 15%, 25%, or 30% of the code can be missing or unreadable and still decode successfully.
Why do QR codes have three big squares in the corners?
Those are position detection patterns. They help the scanner quickly locate and orient the QR code regardless of rotation. The fourth corner has a smaller alignment pattern for additional positioning accuracy.
Related Tools
- QR Code Generator — Create QR codes for URLs, text, WiFi, and more
- Barcode Generator — Generate UPC, EAN, Code 128, and other barcode formats
- Base64 Encoder/Decoder — Encode and decode Base64 strings
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QR Code Scanner FAQ
How do I scan a QR code from a screenshot?
Upload the screenshot to a QR code scanner tool. The scanner analyzes the image pixels to locate and decode the QR pattern. This works with screenshots from phones, computers, or any saved image containing a QR code.
What data can a QR code contain?
QR codes can encode URLs, plain text, WiFi network credentials (SSID and password), contact cards (vCard), calendar events, email addresses, phone numbers, SMS messages, geographic coordinates, and cryptocurrency addresses.
Is it safe to scan unknown QR codes?
Use caution with unknown QR codes. They may link to phishing sites or malicious downloads. Always preview the decoded content before opening URLs. A good scanner shows you the data first without automatically redirecting.
Why won't my QR code scan?
Common reasons: the image is blurry, the QR code is partially obscured, there's not enough contrast, or the QR code is damaged. Try a higher resolution image, ensure the entire code is visible, and check that lighting doesn't create glare.
What's the difference between QR codes and barcodes?
Barcodes are one-dimensional (lines) and hold limited data like product IDs. QR codes are two-dimensional (squares) and can store much more data—up to 4,296 alphanumeric characters. QR codes also have error correction, so they work even when partially damaged.
Can QR codes be scanned from any angle?
QR codes can be scanned at various angles because they contain position markers (the three large squares in corners) that help scanners orient the code. However, extreme angles or perspective distortion may cause scanning to fail.
How much data can a QR code hold?
A QR code can hold up to 7,089 numeric characters, 4,296 alphanumeric characters, or 2,953 bytes of binary data. In practice, most QR codes contain URLs or short text under 300 characters for reliable scanning.
Do QR code scanners store my images?
Browser-based QR scanners that process images locally do not upload or store your images. The decoding happens in your browser using JavaScript. Server-based scanners may upload images temporarily. Check the tool's privacy policy.