QR Code Scannability Tester — upload an image, see if it really scans
Drop in the QR image to compare local decoding of the original, grayscale, boosted-contrast and reduced-size variants. Check the returned content. This examines digital files, not real camera distance, paper or lighting; use a physical sample before printing a batch.
Up to 25 MiB / 16 megapixels. Animated images use the browser’s displayed frame.
Your image and its content stay in this browser.
How to use the qr code scannability tester?
- 1Drop the QR image in or click to upload (you can also paste a screenshot).
- 2QR Cat runs several local preprocessing passes and tries to decode each.
- 3Review the content read by each digital check, including unreadable or incomplete results, and compare it with the original or your expected content.
- 4Follow the advice: usually boost contrast, leave enough quiet zone, or print the code larger.
Why use QR Cat's QR Code Scannability Tester?
- Catch broken codes early: many codes look fine but won't scan — find out before it's printed and on a wall.
- Digital image variants: compare original, grayscale, boosted-contrast and reduced-size decoding. These transformations are not physical distance, lighting or print tests.
- Use the results to inspect incomplete patterns, cropped margins, dense content or small modules. These troubleshooting hints are not a print certification.
- Image never uploaded: every test runs locally in your browser; your code never leaves your device.
Frequently asked questions
How is 'scannability' actually measured?
ZXing attempts to decode the original image and digital variants, then compares the returned content. Passing these checks does not establish compatibility with every phone, lighting condition or print material. Test the actual export on the intended devices.
What does it mean when only some digital checks pass?
It means some digital checks did not produce stable, matching results. It does not predict a particular phone or camera distance. Check the content, image quality and margins, then test the downloaded file and a physical sample.
How are contrast and quiet zone judged?
Image-wide brightness and light corners are clues, not measurements of module contrast or proof of a four-module quiet zone on every edge. Inspect the complete exported code and use actual decoding and a physical sample to check it.
Why do some codes scan at full size but fail when shrunk?
Longer content means denser modules; once shrunk, adjacent modules blur together and the camera can't tell them apart. Fix it by shortening the encoded content (e.g. a short link) so modules are sparser, or simply print the code larger and closer to the scanner.
Is the image uploaded?
No. The uploaded QR image is processed only in your browser's local memory; all preprocessing and decoding happen on your device and are discarded when done — nothing uploaded or stored.
Updated · QR Cat team
Sources, review and limits
Last verified
2026-06-17
Author
Ziyao Wang — Builder & editor, QR Cat
Review method
Maintainer self-review. Verify the downloaded content and test on your intended devices before distribution.
Primary sources
- QR-code encoding rules based on ISO/IEC 18004 concepts
- Browser Canvas and SVG export APIs
- User-entered URL, text, Wi-Fi or contact payloads
QR codes should be tested on target devices before print or distribution. We do not validate the safety, ownership or legality of the destination you encode.