Want to Know a QR Code's Error Correction Level? I Built an App That Makes It Easy

Ken Kubomi — Wed, 17 Jun 2026 14:08:59 +0000

When creating QR codes, have you ever wondered whether you should use error correction level Q or H for better reliability? Or perhaps you've thought that level L might produce a smaller QR code that's easier to scan.

You may also have encountered situations where someone asked you to match the settings of an existing QR code or make it compatible with one generated by another company's software.

However, when I actually tried to find out which error correction level an existing QR code was using, I realized there wasn't a simple way to do it. As both a learning project and a practical tool, I decided to build an app that lets you scan a QR code and instantly view its detailed internal information.

Instantly View Detailed QR Code Information

Simply scanning a QR code reveals information such as:

Error correction level (L / M / Q / H)
Model (1 or 2)
Version (1–40)
Number of modules (21×21–177×177)
Mask pattern (000–111)

The app also makes decoded text easier to inspect by visualizing ASCII characters and spaces correctly, allowing you to understand the exact contents of the QR code and copy any selected range directly.

Visualize the QR Code Bit Stream

The app also includes a feature that lets you visually inspect the bit stream stored inside a QR code.

You can clearly see how the QR code is structured, including the mode indicator, character count indicator, encoded data, and other bit sequences. This makes it much easier to understand how QR codes are actually encoded internally.

Recreate the Original QR Code Image

Another feature allows you to regenerate a clean PNG or SVG image with exactly the same module layout as the scanned QR code.

Even if the original image has become blurry due to printing, JPEG compression, or repeated editing, as long as the app can successfully decode the QR code, it can recreate a clean image with the identical module arrangement.

After exporting the image, you are free to change its colors or make the background transparent.

Even QR codes with poor image quality like this can be restored, as long as they remain readable.

Download

If you'd like to try the app, you can download it here.

iOS
https://apps.apple.com/app/id6749790356

Android
https://play.google.com/store/apps/details?id=jp.samustream.qrparser

Final Thoughts

The app was designed with professional use in mind and does not collect any usage analytics or personal data. Because of this, I have no way of knowing how people are using it.

If you have any suggestions, ideas for improvements, or feedback, I'd be delighted to hear from you. Reviews on the app stores are also greatly appreciated.