Online Duplicate Number Filter

Online Duplicate Number Filter

Offers three distinct frequency-based outputs for a parsed number list. Deduplicate returns every distinct value once; Duplicates only returns distinct values occurring more than once; Appears once returns values whose count is exactly one. First-occurrence order is preserved in every mode.

Verified input 1, 2, 2, 3: Deduplicate returns 1, 2, 3; Duplicates only returns 2; Appears once returns 1, 3. Repeated values are not repeated in the duplicate-only result, and the tool does not report counts.

Equality is based on parsed JavaScript Number keys, so different textual representations of the same value combine and positive/negative zero share one key. Output is normalized to the page's decimal separator with up to 15 significant digits rather than preserving original text.

Input uses regional numeric parsing and is capped at 100,000 characters and 10,000 finite values. An invalid output-mode value is rejected. The tool does not perform approximate matching, sort results, compare a second list or preserve leading zeros.

Filtering is browser-local with no server or AI. Use a text-line duplicate tool for identifiers, phone numbers or codes whose exact characters matter, and an audited data workflow when duplicate counts or provenance must be retained.