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01JSON Formatter & Validator02JSON Path Builder03JWT Decoder04Base64 Encode / Decode05URL Encode / Decode06Unix Timestamp Converter07SQL Formatter08CSV ↔ JSON Converter09CSV Duplicate Processor10Markdown → HTML Converter11Regex Tester12HTML Formatter / Minifier13Character & Byte Counter14Japanese Era ↔ Gregorian Converter15Katakana ↔ Hiragana Converter16Japan Postal Code Lookup17Character Encoding Inspector (UTF-8)18XML ↔ JSON Converter19YAML ↔ JSON Converter20HTML Entity Encoder / Decoder21SQL IN Clause Generator22Date Difference Calculator23Japan Phone Number Formatter24CSV Column Extractor25CSV Merger26Text / JSON Diff Viewer27SQL INSERT Generator28SQL Function Reference29SQL Query Analyzer30Business Day Calculator31Power Query Code Generator32Japan Address Splitter33UUID Generator34Hash Generator (SHA-256 / SHA-512)35Number Base Converter (2 / 8 / 10 / 16)36Cron Expression Parser37Color Code Converter (HEX / RGB / HSL)38QR Code Generator39Image Resizer40Image Compressor41PDF Merger

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csv dedup deduplicate remove duplicates clean data

CSV Duplicate Processor

Remove duplicate rows from CSV to get clean data, or extract only the duplicate rows to review them. Useful for deduplication and data cleaning.

USAGE

3 simple steps

  1. 1Paste your CSV data
  2. 2Select a processing mode
  3. 3Click the Process button to see the result

FAQ

Frequently Asked Questions

Q. How are duplicates defined?

A. Rows where every column value is exactly the same are considered duplicates. Comparison is case-sensitive.

Q. Does the header row count as a duplicate candidate?

A. Yes. All rows including the first are evaluated. In practice the header row rarely matches a data row, so this is usually not an issue.

Q. How many rows can be processed?

A. Processing runs in the browser, so tens of thousands of rows work fine. For hundreds of thousands, a spreadsheet application is recommended.

Related Tools

CSV ↔ JSON ConverterCSV Column ExtractorCSV Merger