Processed locally
Your input stays in this browser.
Start with the object being identified
A barcode is an agreement between a printed object, a reader and a receiving record. A checkout unit, a carton, a warehouse tote and an internally tagged instrument can all carry dark bars, yet each calls for a different identifier. Retail shelf items use allocated GTIN representations: EAN-13, UPC-A and EAN-8. A shipping case uses ITF-14 to identify its packaging level. Serial strings, work orders and asset labels may instead need the broader character repertoire of Code 128 or the restricted industrial alphabet of Code 39. Select the identifier before choosing a compact-looking pattern.
Separate allocation from arithmetic
Several retail formats end with a modulo-10 check digit. The calculation catches many transcription mistakes, but it does not assign a company prefix, establish product ownership or decide which package level a number describes. A checksum can be correct on a label for the wrong item. Keep the approved source identifier, its intended representation and the product record together. The check-digit calculator is useful for testing a supplied sequence; it is not a registry.
Match the carrier to the workflow
EAN-13 and UPC-A are point-of-sale representations, while EAN-8 exists where a small package cannot carry a larger symbol at a readable module width. ITF-14 is designed for outer cases and often includes bearer bars for corrugated handling. Code 128 switches code sets to compress numeric runs in operational strings. Code 39 trades density for a simple, limited character alphabet. GS1-128 adds application identifiers and separators so a scanner can distinguish a trade item, date and lot. Codabar, MSI Plessey and Pharmacode are specialised legacy or controlled-process carriers with their own reader settings and rules.
Print geometry is part of the data path
Bars are only readable when their widths, spaces and quiet zones survive the final production process. A vector export protects the source geometry, but a layout application can still crop margins, stretch one axis, introduce a low-contrast background or rasterize at an unsuitable resolution. Corrugate, curved containers, thermal transfer and glossy coatings fail differently. Test the exported artwork at its final size on the material and scanner that the real workflow uses; a phone-camera scan of a desktop preview is not a receiving or checkout test.
What the local tools do and do not decide
These forms validate the declared character rules or length, perform the format's documented arithmetic where applicable, and create an SVG in the browser. They do not send the entered value to this site. The result cannot approve a GS1 allocation, interpret a product catalogue, validate a pharmaceutical release, or guarantee a trading partner's scanner configuration. Treat a refused input as a signal to inspect the source record, rather than changing digits until a barcode appears.
Use a proof record that another person can repeat
For a production label, retain the source value, selected symbology, generated file, print settings and the string expected from the destination reader. That small record separates three different failures: an invalid identifier, artwork whose modules were altered, and a scanner or parser configured for another carrier. It also prevents a clean-looking replacement label from silently breaking the link between a physical package and the system that owns its data.
Worked choice: three scans on one shipment
A producer ships 24 retail jars in two corrugated cases of 12. The jar needs the approved EAN-13 or UPC-A representation that checkout expects; the case needs its approved case-level identifier; and a pallet that must be individually tracked may need an SSCC workflow. Start by writing those three objects in a release record, then test each with the reader that consumes it. A checkout scan returning the jar record does not prove that receiving can identify the case, and a case scan does not serialise a pallet. GS1's logistic-label guidance distinguishes carton trade-item labels from logistic-unit identification: https://ref.gs1.org/guidelines/logistic-label/.
Keep leading zeroes as data, not decoration
Barcode values should be stored as text with their intended length. A spreadsheet can turn UPC-A 036000291452 into 36000291452 before anyone sees a warning, while a 14-character interchange field can add filler zeroes to a shorter GTIN representation. Neither transformation tells a designer which bars to print. Retain the source value, carrier, package level and human-readable form separately. Then compare the decoder result character for character with the approved representation. Arithmetic can catch a mistyped final digit, but it cannot recover a leading zero discarded by an import or determine whether the changed string belongs to the correct product.
Investigate the failed layer, not the nearest number
When an SVG scans on screen but not on a finished label, keep the source digits fixed and inspect the physical layer: quiet zones, scale, contrast, ink spread, curvature, corrugation, seams and the actual scanner. When a symbol scans but retrieves the wrong record, inspect allocation and master data. When a warehouse needs a lot or date that an ITF-14 cannot carry, inspect the required field contract rather than squeezing extra meaning into a GTIN. Record the failed sample, reader, returned string and corrective action. That separation keeps a correct barcode from being altered to conceal a printing, system-configuration or packaging-level error.
Release one barcode only with its receiving evidence
For every production symbol, retain a compact proof record: object and package level, approved source value, selected carrier, artwork revision, final material, reader used, returned string and date. A retail jar, a corrugated case and a serialised pallet might all travel in one shipment, but they do not share one identification job. Test the jar at checkout, the case at receiving and the pallet through the logistics process that owns its serial record. When a result fails, this record shows whether to correct allocation, source data, artwork or reader configuration. It also prevents a later operator from treating a calculator result or a browser preview as evidence that a physical label belongs in a live commercial workflow.
Choose the next check from the result
A failed checkout proof calls for a retail-data or print review; a failed dock proof calls for a case-label review; and a missing lot field calls for a carrier that supports structured data. Recording that distinction prevents one barcode tool from being used as a substitute for the system that owns the operational decision.