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Excel Deduplicate

Find duplicate rows in an Excel or CSV file by the columns you choose, ignoring the variations you choose, then remove them or merge each group into one row. Review every group, change which row survives, and save as Excel or CSV.

On-device・No upload

Your files and input are processed only inside your browser on this device and are never uploaded to our servers.

Drop a file here

or

Files are processed in this browser on your device and never uploaded.Accepts: Excel (.xlsx) / CSV / TSVUp to 100 MB per filePaste (Ctrl+V) also works

How to use

  1. Drop an Excel (.xlsx), CSV or TSV file, or click “Choose files”. CSV encodings (UTF-8, Shift_JIS, …) are detected automatically.

  2. Under “Key columns”, pick the columns that define a duplicate (e.g. company name or e-mail). With none selected, every column must match.

  3. Under “Variations to ignore”, choose whether case, spacing, full-/half-width, phone-number hyphens, company suffixes and so on should be ignored.

  4. Choose the row to keep (first, last, most filled-in, newest date, largest value, …) and whether to remove or merge. When merging, pick per column whether to fill blanks, join values, sum and more.

  5. Review each duplicate group and change the kept row by hand if needed.

  6. Choose the table to save (result, duplicates only, or with flag columns) and the format, then download.

What it does

Matching that ignores real-world variations

Optionally ignore full-/half-width characters, extra or all spaces, invisible characters, hiragana vs katakana, letter case, hyphens/brackets/+81 in phone numbers, company designators (“Inc.”, “Co., Ltd.”, “株式会社”, “(株)”, “㈱” …), number formatting (“1,000” = “1000”) and date notation (“2026/1/4” = “令和8年1月4日”).

Choose the surviving row — by rule or by hand

Keep the first or last row, the most filled-in row, the newest or oldest date in a column, or the largest or smallest value. Every group can be opened and the kept row changed with one click.

Merge instead of delete

Combine each group into one row. Per column choose “kept value (fill blanks from others)”, “join distinct values”, “sum”, “maximum” or “minimum”, and optionally add a “rows merged” column. Each group shows a preview of the merged row.

Three result tables

The deduplicated (or merged) table, a duplicates-only table grouped together, and the original table with “Duplicate group” and “Status” columns. Preview them, then save as Excel (.xlsx, optionally all three as sheets) or CSV.

Large files stay responsive

Matching runs in a Web Worker, so tables of around 100,000 rows are processed without freezing the page. Rows, groups and rows removed are shown at a glance.

Use cases

  • Consolidate a customer list collected from several teams where “ABC Co., Ltd.” and “ABC Inc.” are the same company
  • Remove repeat sign-ups from an event list, including e-mail addresses that differ only in case
  • Merge rows for the same client into one, summing amounts and joining notes
  • Share a copy of the table with duplicate flags before deleting anything
  • Match a contact list where phone numbers are written as 03-1234-5678, 03(1234)5678 or +81-3-1234-5678

Supported formats

Input

Excel (.xlsx / .xlsm)CSV (.csv)TSV (.tsv / .txt)

Output

Excel (.xlsx, multiple sheets)CSV (UTF-8 with BOM / UTF-8 / Shift_JIS / EUC-JP / UTF-16)

Capability matrix

FeatureSupportNotes
Duplicate detection by chosen columns (combined keys)Supported—
Ignore width, spaces, case and kana differencesSupported—
Ignore phone formatting and company designatorsSupportedDesignator position is ignored
Keep-row rules plus manual override per groupSupported—
Merge into one row (fill, join, sum, max, min)Supported—
Flagged table and duplicates-only tableSupported—
Fuzzy matching of similar values (typos, abbreviations)Not supportedValues must match exactly after normalisation
Duplicates across sheets or filesNot supportedOne sheet at a time
Keep formatting, formulas, merged cellsNot supportedFormulas are exported as their values
Legacy Excel (.xls)Not supportedRe-save as .xlsx in Excel first

Limits & notes

  • Up to 100 MB and 3 million cells per file. About 100,000 rows are matched in a few seconds, depending on your device.
  • The group list shows 20 groups at a time and the first 40 columns of each group. Saved files always contain every row and column.
  • Values that are merely similar (typos, abbreviations) are not matched — matching is exact after the normalisation you select.
  • Saved files contain cell values only. Formatting, formulas and merged cells are not carried over.

Privacy & safety

Reading, matching and building the download all happen in your browser. Your data is never sent to or stored on a server.

FAQ

How do I remove duplicates in Excel based on one column?
Open the file and select only that column (for example the e-mail address) under “Key columns”. Rows with the same value form a duplicate group, and one row per group is kept according to the keep rule.
Can “ABC Inc.” and “ABC Co., Ltd.” be treated as the same company?
Yes. Tick “Ignore legal-entity designators in company names”. Designators such as “Inc.”, “Corp.”, “Co., Ltd.”, “株式会社”, “(株)” and “㈱” are removed before comparing, wherever they appear.
Can I merge duplicate rows instead of deleting them?
Yes. Choose “Merge into one row”. Blanks in the kept row are filled from the others, and per column you can join distinct values, sum, or take the maximum or minimum.
Can I choose which duplicate to keep?
A rule picks the row automatically — first, last, most filled-in, newest date, largest value and more — and you can override it for any group in the duplicate list.
How is this different from Excel’s “Remove Duplicates”?
Excel removes exact matches and always keeps the first row. This tool can ignore spelling variations, lets you choose or merge the surviving row, and shows and exports the groups before anything is deleted.
Is my data uploaded?
No. Everything runs in your browser and your data never leaves your device.

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