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Duplicate Row Finder

Detect exact duplicate rows or duplicate keys in a loaded CSV file without uploading the dataset.

Local browser-side processing

Your selected file is processed locally in your browser. ScholarTool does not upload the file to a third-party calculation or data-analysis API.

1. Select and load CSV

Selecting a file only records file details. Click Load CSV to parse and preview input.

Choose CSV fileAccepted: .csv, text/csv, and compatible plain-text CSV files. Limit: 25.0 MB.

Drag and drop is optional; the normal file chooser is the primary accessible control.

DelimiterHeader rowSkip empty linesCommon missing tokens

Custom missing tokensTrim for missingCase-sensitive

2. Configure and run tool

Results, visuals, downloads, and copy actions remain hidden until Find Duplicate Rows succeeds.

Load a CSV file to enable processing options.

What This Tool Does

The Duplicate Row Finder supports exact full-row matching and selected key-column matching. It reports duplicate groups, source row positions, and a deduplicated export using keep-first or keep-last rules.

Duplicate detection method

Duplicate groups are built from either every column or selected key columns. Matching is exact after optional whitespace trimming and does not perform fuzzy matching.

Worked Example

Load a transaction CSV and select invoice_id plus line_number as key columns to find repeated records before exporting a keep-first deduplicated copy.

Common Mistakes

Using full-row matching when duplicate identity is actually defined by a smaller business key.
Expecting fuzzy name matching; this tool intentionally uses exact matching.
Removing duplicates before checking which row should be retained.

Limitations

No fuzzy matching, phonetic matching, or record-linkage scoring is performed.
Whitespace trimming changes duplicate keys only for matching, not the original loaded dataset.
Deduplicated CSV output should be reviewed before replacing source data.

References

RFC 4180: Common Format and MIME Type for Comma-Separated Values (CSV) Files.
Papa Parse documentation: Official Papa Parse CSV parsing documentation for browser and JavaScript workflows.
MDN File API: MDN documentation for browser File API concepts used by local file selection.

Exact versus key duplicates?

Full-row duplicates match every column. Key duplicates match only selected identifier columns such as ID and date.

Keep first versus keep last?

Keep first retains the earliest source row in each duplicate group. Keep last retains the latest source row.

Are spaces ignored?

Only when the trim whitespace option is enabled for duplicate matching.

Does it support fuzzy duplicates?

No. This tool deliberately performs exact matching to avoid unsafe automatic merges.

Is original order preserved?

Yes. Deduplicated exports are returned in original source-row order after the keep rule is applied.

Are CSV files uploaded to ScholarTool?

No. The selected CSV file is read and processed locally in your browser. ScholarTool does not upload the file to a third-party calculation or data-analysis API.

Can the tool handle large CSV files?

The browser-local workflow enforces a 25 MB file limit, 200,000 parsed-row limit, 250-column limit, bounded previews, and bounded result tables to avoid freezing the page.

Engineering disclaimer

This tool is intended for educational, estimation, and preliminary data-preparation use. Always verify critical data-processing decisions with validated workflows and qualified professional judgment before using results in real research, compliance, or engineering decisions.

Need Professional Support?

ScholarTool is powered by ScholarEase Consultancy Services LLP. Professional engineering, simulation, research, and technical documentation support is available through the connected services website.

Visit ScholarEase

Last reviewed: 2026-07-02

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What This Tool Does

Duplicate detection method

Duplicate groups are built from either every column or selected key columns. Matching is exact after optional whitespace trimming and does not perform fuzzy matching.

Duplicate Row Finder

Local browser-side processing

1. Select and load CSV

2. Configure and run tool

What This Tool Does

Duplicate detection method

Worked Example

Common Mistakes

Limitations

References

Related Tools

Engineering disclaimer

Need Professional Support?

Duplicate Row Finder

Local browser-side processing

1. Select and load CSV

2. Configure and run tool

What This Tool Does

Duplicate detection method

Worked Example

Common Mistakes

Limitations

References

Related Tools

Engineering disclaimer

Need Professional Support?