GST CONSOLE · UTILITIES
Invoice sequence checker
Find gaps and duplicate invoice numbers separately for each observed series.
Files are processed in this browser only. They are not uploaded, saved to your workspace or sent to external services. Clear files when finished. Up to 5 MB/file, 20,000 rows and 500,000 cells; visible XLSX sheets or CSV, first non-empty row is the header.
Use one business and financial year per file. Series are grouped by prefix, suffix and digit width using the final numeric part. Gaps cover only the observed first-to-last range. A gap is a review item, not proof of a missing sale; retain cancelled invoice evidence.