How a barcode stores information
A barcode is a pattern of bars, spaces or small squares that encodes a short string of characters. A scanner does not read the picture itself. It measures the widths and positions of the dark and light elements, matches them against the rules of a particular symbology, and converts them back into the original text or number.
Different symbologies exist for different jobs. Retail products usually carry a numeric code, shipping labels and inventory tags often use compact alphanumeric formats, and two-dimensional codes such as QR hold much more data in a square grid. The decoded value is only an identifier or a piece of text. The barcode does not contain a product name or a price, it simply points to a record stored somewhere else, such as a catalog or database.
When you would read a barcode from an image
Sometimes the barcode is already in a file: a screenshot of a ticket, a photo of a package label, a scanned document, or an image someone emailed you. Reading it from the picture saves you from retyping a long number by hand, which is slow and easy to get wrong.
Typical cases include copying a tracking or serial number off a label photo, checking what value a generated code actually contains before printing it, pulling an identifier out of a screenshot for a spreadsheet, or confirming that a code you made renders correctly.
How to read a barcode with this tool
- Open the tool and drag an image onto the upload area, or click the area to choose a file from your device.
- The image appears on the left and the page shows "Scanning..." while it looks for a code.
- If a code is found, the Decoded value appears on the right in a monospaced box.
- Click the copy icon beside the value to put it on your clipboard. The icon changes to a check mark for a moment to confirm.
- If nothing is found, you will see a message suggesting a clearer, more direct photo. Reload the page to try a different image.
Decoding runs in your browser using a barcode-reading library that is loaded when you upload a file. The image is not sent to a server by the tool.
Tips and limits
The tool returns a single decoded value per image. If a photo holds several codes, you get at most one result, so crop the image to the one you want first with the Crop Image tool.
For best results, photograph the code straight on, in even light, and make sure it fills a good part of the frame. Avoid reflections on glossy labels. A very small code inside a large image can fail even though it looks fine to your eye, and cropping closer often fixes that.
The page labels its messages for barcodes, but the underlying reader handles several code types, and QR codes are part of that. If your image holds a QR code, the dedicated QR Code Scanner is the better-named place to go.