QR Validator

The QR code version (1 through 40) determines the physical size of the code in modules. Version 1 is 21×21 modules, and each subsequent version adds 4 modules per side, up to version 40 at 177×177 modules. Higher versions can store more data but require more space to print or display. Knowing the version helps you understand whether a QR code has sufficient capacity for your data.

The number of modules per side is calculated as 17 + (4 × version). For example, version 1 has 21 modules per side (17 + 4), version 3 has 29 modules (17 + 12), and version 40 has 177 modules (17 + 160). The total number of modules is the square of this value.

Finder patterns are the three square markers located at the top-left, top-right, and bottom-left corners of every QR code. They help scanners detect the QR code, determine its orientation, and establish the coordinate system for decoding. A valid QR code always has exactly three finder patterns. The tool highlights each one with a different color so you can verify they are all present.

The green bounding box outlines the perimeter of the decoded QR code, connecting all four corners (top-left, top-right, bottom-right, bottom-left). This visual overlay helps confirm that jsQR detected the correct code boundaries on the image.

Standard QR codes use a light background with dark modules. Inverted (or negative) QR codes use a dark background with light modules. Some stylized or artistic QR codes invert the colors. The tool first attempts standard decoding, and if that fails, it tries inverted decoding as a fallback. The result card shows whether the code was decoded in "Standard" or "Inverted" mode.

The tool supports PNG, JPEG, WebP, GIF, and BMP image formats up to 20 MB in size. Images are automatically scaled down to a maximum of 4096 pixels on the longest side before analysis to ensure fast decoding while maintaining detection accuracy.

No. Everything runs entirely in your browser using client-side JavaScript. When you select an image, it is read locally using the FileReader API and processed in memory. No image data, decoded content, or structural information is ever uploaded to any server or transmitted over the network.

The estimated data capacity shows the maximum number of bytes that a QR code of the given version can store when using the lowest error correction level (L-level, ~7% recovery). Actual capacity depends on the error correction level and the character encoding mode used. The value shown is for byte mode with L-level error correction, representing the maximum for that version.

The jsQR library includes error correction that can handle minor damage, low print quality, and moderate blur. The tool also retries decoding with inverted colors for stylized or negative QR codes. However, severely damaged codes or codes with significant distortion may not decode.

The current version does not extract the error correction level from the QR code metadata. Only the version, module count, and data capacity estimate are displayed. Error correction level extraction may be added in a future update.

The jsQR library supports QR codes up to version 40. If your QR code uses a version higher than what jsQR supports, or if the image resolution is too low to resolve individual modules, decoding may fail.

Yes, the tool is completely free with no usage limits, no sign-ups or registration required, and no advertisements. All validation happens locally in your browser, so you can validate as many QR code images as you like.

Yes. The validator can be used as part of a QA workflow to verify that generated QR codes have the correct structure, all three finder patterns are present, the bounding box is properly aligned, and the version matches expectations for the data payload size.

After decoding, a canvas overlay is drawn on top of the image preview. The green bounding box connects the four corner coordinates returned by jsQR. The three finder patterns are marked with colored circles (red for top-left, blue for top-right, yellow for bottom-left). The overlay scales dynamically with the displayed image size.