ZPL debugger

How to debug a ZPL file line by line

1. Paste the ZPL exactly as your system sends it to the printer — a spool file, an ERP export or a label handed over by a carrier all work. Set the real label size and density: findings about clipping and out-of-label fields depend on them.
2. Press Debug. The same rule engine behind the diagnostics hub runs once, and every finding comes back with a line and column instead of a summary.
3. Read the annotated source. Lines with errors are tinted red, lines with warnings amber, and each note sits directly under the line it belongs to — including the suggested fix where the engine has one, such as deleting an unknown command.
4. Fix the first structural error before judging the rest. An unbalanced ^XA/^XZ or a missing ^FS early in the file often produces a cascade of findings that disappear once the first one is corrected.

When this is the right tool

Use the debugger when you already know the label is broken and need to find the exact line — a job that prints blank, a template that lost a field after an edit, a file from an ERP merge where one of forty lines is wrong. The line-by-line view answers "where" faster than a sectioned report, because you read the finding in the context of the code that caused it. When you want the opposite — an overall verdict with a score, section by section — the ZPL diagnostics hub presents the same engine's findings that way instead.

Frequently asked questions

• What is the difference between the debugger and the diagnostics hub? — Same engine, different presentation. The hub groups findings into sections (syntax, size, barcodes, fonts…) and computes an honest score; the debugger pins each finding to the source line that caused it. "How healthy is this label" versus "which line is wrong".
• Does the debugger change my ZPL? — No. The tool is read-only: it reports findings and shows the suggested fix as text where one exists, but your input is never modified, stored or logged — the request is stateless.
• Why do findings depend on the label size I enter? — Because several rules measure the label against its physical size: a field at x=5000 is fine on a wide label and out of bounds on a 4-inch one, and dots mean different distances at 203 and 300 dpi. Enter the real size to get findings that match your printer.