About the QR Code Scanner
This QR code scanner reads QR codes from an uploaded image, a pasted screenshot or your device camera and decodes them entirely in your browser — nothing is uploaded to a server. Besides the raw text it shows the symbol’s version, error-correction level and how many damaged bytes were repaired, which is useful when testing printed codes.
It then explains what the code would do if you scanned it with a phone: open a website, join a Wi-Fi network (with the network name, security type and password laid out), save a contact card, add a calendar event, send an email or text, open a map location, add a two-factor authentication account or request a crypto payment. Safety checks flag unencrypted links, raw IP addresses, link shorteners and look-alike punycode domains, which are common in QR phishing (“quishing”).
Use it to read a QR code on your computer screen, check a code before trusting it, recover a Wi-Fi password from a printed card, or debug codes you generate. The decoder handles rotated and slightly skewed photos; very small, blurry or heavily distorted codes may need a sharper, closer image. You can also paste decoded text into the box to analyse it.
How to use the qr code scanner
- 1Click “Upload image”, drop a picture, or paste a screenshot with Ctrl/Cmd + V.
- 2Or press “Use camera” and hold the QR code steady in front of it.
- 3Read the decoded content and what it would do on a phone.
- 4Check the safety notes before opening links or joining networks.
- 5Copy the raw text or the individual fields you need.
Formula and method
The scanner converts the image to grayscale and applies a local threshold so uneven lighting does not hide modules. It searches every row for the 1:1:3:1:1 dark-light-dark-light-dark ratio of the three corner finder patterns, confirms them vertically, estimates the module size along the lines between them and from that the symbol size (21 to 177 modules). For version 2 and larger it also locates the bottom-right alignment pattern, then maps the grid through a perspective transform and samples each module.
Following ISO/IEC 18004 it reads the BCH-protected format information (error-correction level and mask), the version information for version 7+, removes the mask, reads the codewords in the zig-zag order, de-interleaves the blocks and corrects errors with Reed–Solomon decoding over GF(256) — up to about 7%, 15%, 25% or 30% of codewords for levels L, M, Q and H. Numeric, alphanumeric, byte (UTF-8 or ECI-declared encodings) and Kanji segments are then decoded to text.
Worked examples
Wi-Fi login card
Wi-Fi QR codes use the WIFI: format with T (security), S (network name) and P (password) fields separated by semicolons. This one joins the WPA network "Cafe Guest" with the password latte2026.
Shortened http link
The code opens a bit.ly short link over plain http. Both are flagged: the connection is not encrypted, and the shortener hides where you will really end up, so preview or expand the link before trusting it.
Authenticator app setup
otpauth:// codes enrol an account in an authenticator app. The tool shows the issuer (Example), the account, and the defaults SHA1, 6 digits and a 30-second period — and warns that the embedded secret must stay private.
Frequently asked questions
How do I scan a QR code on my computer?+
Take a screenshot of the code (Win + Shift + S on Windows, Cmd + Shift + 4 on Mac), then paste it into this page with Ctrl/Cmd + V, or upload a saved image. You can also use your webcam with the camera button.
Is it safe to scan QR codes online?+
This scanner decodes images in your browser and uploads nothing, and it never opens the link for you. The risk is the destination: check the domain, avoid shortened or http links you do not trust, and never enter passwords after scanning a code from a poster or email.
Why can’t my QR code be read?+
Common causes are blur, glare, a code that is too small in the photo (each module should be at least 2–3 pixels), a missing quiet zone around the code, or strong perspective. Crop closer, retake the photo straight on, or try a higher-resolution image.
Can I see the password from a Wi-Fi QR code?+
Yes. Wi-Fi QR codes store the network name, security type and password in plain text in the WIFI:T:…;S:…;P:…;; format, so scanning the code here shows the password directly.
What do QR versions and error-correction levels mean?+
The version (1–40) sets the grid size, from 21 × 21 to 177 × 177 modules, and therefore the capacity. The error-correction level (L, M, Q, H) controls how much of the code can be damaged and still read: roughly 7%, 15%, 25% and 30%.