Practical guide
Which code type should you use?
Start with the system that will read the code. A symbol can be perfectly valid and still be wrong for the receiving software, scanner or business process. This guide separates the common formats, the checks they support and the output choices that matter after generation.
Choose by payload and receiving system
Do not select a format because it looks familiar. Ask what data must be carried and what the destination is configured to accept. A phone camera naturally handles QR codes and links. A warehouse scanner may be configured for Code 128 only. A retail checkout expects a properly allocated EAN or UPC identifier—not an arbitrary SKU drawn as an EAN symbol.
| Format | Good fit | Important boundary | Tool |
|---|---|---|---|
| QR Code | Links, free text, Wi-Fi details, contact data and Unicode read by phones or 2D scanners. | It encodes data; it does not host a PDF, photo or video. Large files need a hosted link. | Create |
| Code 128 | Compact internal asset, stock, shipment or serial identifiers using printable ASCII. | It does not turn an internal SKU into an allocated retail identifier. | Code 128 |
| Code 39 | Legacy systems that explicitly require its restricted character set. | It is usually wider than Code 128 for comparable data. Confirm the receiver requires it. | Create |
| EAN-13, EAN-8, UPC-A | Retail workflows using an identifier supplied by the appropriate numbering authority. | A correct check digit proves arithmetic structure, not allocation, ownership or product authenticity. | EAN-13 |
| ITF | Even-length numeric data where the receiving system explicitly expects Interleaved 2 of 5. | It is not a general text format and should not be selected solely because a value is numeric. | Create |
| GS1-128 or GS1 Data Matrix | Structured GTIN and supported traceability fields such as expiry, lot and serial. | The builder encodes identifiers you supply; it does not allocate a GTIN or GS1 company prefix. | GS1 Builder |
| Data Matrix, PDF417, Aztec | Existing symbols that need to be decoded from an image or camera. | General generation for these formats is not exposed. The Scan tool decodes them; the guided builder generates GS1 Data Matrix. | Scan |
Five questions to answer before encoding
- What will read it? Record the scanner model or phone app and the receiving software. A scanner can support a symbology while its current configuration disables it.
- What exact value must arrive? Leading zeroes, letter case, spaces and control separators can be significant. Test the received value in the destination field, not only the scanner beep.
- Is the identifier internally assigned or externally governed? Internal asset numbers can use Code 128 or QR. Retail and GS1 workflows need identifiers allocated outside this tool.
- How much physical space is available? More data creates denser QR codes and wider linear barcodes. The minimum useful size depends on the printer, material, contrast and scanner.
- Will the code be displayed, printed once or produced in a batch? That determines whether PNG, SVG, a PDF sheet or ZPL is the appropriate output.
When the receiver accepts more than one format, use the least complex symbol that carries the required data with comfortable physical dimensions. Automatic detection is a helpful starting point for common inputs; it cannot know a private warehouse or retail system's integration contract. Override it when that contract specifies a carrier.
Choose an output for the next production step
The symbol type and file type solve different problems. Code 128 versus QR decides how data is encoded. SVG versus PNG versus PDF or ZPL decides how that rendered code moves through a layout, print or device workflow.
| Output | Prefer it when | Watch for |
|---|---|---|
| SVG | A code must scale in a design or print layout without raster blur. | Keep it self-contained and preserve its quiet zone; do not edit bars or modules manually. |
| PNG | A fixed-size raster is needed for a screen, document or system that does not accept SVG. | Avoid repeated resizing and compression. Export near the final display size. |
| ZIP | A batch needs one deterministic file per row plus a report. | Review invalid rows, duplicates, filename collisions and verification scope before distributing it. |
| PDF labels | Printing A4, US Letter, known Avery geometry or a custom sheet grid. | Print at Actual size, calibrate both axes and test the stock alignment before a full run. |
| ZPL | A compatible thermal printer accepts a command job with known media size and DPI. | Match printer resolution and test firmware, darkness, speed and media. A browser preview is not a hardware proof. |
For many values, use Batch to map source columns and review row errors. Use Labels only after the values are correct; page geometry cannot repair bad source data.
Validation, digital verification and physical testing are different
Validation checks a format's rules before rendering. For example, EAN and UPC use a check digit; Code 39 has a restricted character set; ITF needs numeric data with an even number of digits. Passing those rules does not query a product database or confirm who owns an identifier.
Round-trip verification renders the current code, decodes that fresh digital output with a separate decoder and compares it with the intended value. It catches important generation and customization failures. The exact local checks and sampling rules are documented in the verification methodology.
A physical scan test checks the part software cannot reproduce: the target printer, driver scaling, ink or thermal darkness, surface, curvature, lighting, distance, camera and scanner configuration. Important labels need this final test on the production equipment. None of these checks is a product lookup; a valid number and a readable image can still describe the wrong item if the source data is wrong.
Troubleshoot the physical cause, not just the file
| Problem | Why it happens | Useful correction |
|---|---|---|
| Code touches nearby artwork | The required blank quiet zone was cropped or covered. | Restore blank space around every edge; do not use the quiet zone as a border or text area. |
| Looks stylish but will not decode | Low contrast, transparent background, altered modules or an oversized centre logo removed information. | Return to dark foreground on a light solid background and simplify customization. |
| Screen works, print fails | Driver scaling, dot gain, thermal darkness, material or glare changed the symbol. | Print at the intended size, calibrate, increase module or bar width and test the actual stock. |
| Linear barcode is too wide | The value is long, bars are appropriately wide, or a legacy format is inefficient for the data. | Do not squeeze bars below guidance; shorten the internal value or confirm whether Code 128 or a 2D carrier is accepted. |
| Leading zero disappeared | A spreadsheet stored the identifier as a number instead of text before import. | Correct the source workbook, format identifier columns as Text and re-import before generation. |
| Valid code gives no product details | A barcode carries an identifier, not an embedded public database record. | Connect the receiving system to the authoritative catalogue; do not infer identity from checksum validity. |
Four practical workflow examples
Guest Wi-Fi card: use QR because phone cameras understand the Wi-Fi payload. Generate it on the main page, keep a clear quiet zone, print a sample and connect with both iOS and Android devices. Avoid displaying a sensitive private-network password in a public area merely because the tool processes it locally.
Internal asset labels: if handheld scanners and the asset system accept
Code 128, encode short stable IDs such as ASSET-0042. Generate a sequence in
Batch, keep the label text human-readable, remove or retain duplicates deliberately, then
scan the printed sample into the actual asset form before producing the full run.
Retail identifier: start with the EAN or UPC supplied for the product. Validate its length and check digit, but do not replace a mismatched digit until the data source is confirmed. A mathematically valid replacement can describe a different number. After generation, preserve the retail symbol's dimensions and test at the point of use.
Lot and expiry traceability: use the guided GS1 builder only when the receiving specification expects the supported Application Identifiers. Supply the allocated GTIN, add lot, expiry or serial data as required, choose GS1-128 or GS1 Data Matrix based on that specification, and compare the displayed element string with the source record.
The local-processing boundary
The anyscan.download tools generate, validate, scan, parse spreadsheets and create exports in the browser. Code values, workbooks and scanned images are not sent to an application backend. The page still requests its static files and may load separately identified advertising on eligible tool pages; this guide itself contains no advertisement code. The privacy page documents that boundary and explains how to inspect it.
Last reviewed: 23 September 2026