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Nablyx

Compare CSV files online free

Nothing uploadedTested up to 200 MB

Compare two CSV files and review added, removed, and changed rows directly in your browser.

Compare two CSV files up to 200 MB each entirely in your browser without uploading them. Match rows with a stable key. The comparison reports added rows, removed rows, and changed rows with before/after values. Files with many short rows and changes across many matched rows can take much longer than files of the same size with fewer rows. The on-screen preview shows at most the first 1,000 differences; download the full diff to inspect the rest.

Processed locally in your browser

Comparison workspace

Choose two CSV files, select a stable key, and compare them locally.

Results will appear here

Select two valid CSV files and run the comparison. Your files stay in this browser.

How to compare CSV files

  1. 1

    Choose your first CSV file.

  2. 2

    Choose the CSV file you want to compare it with.

  3. 3

    Select automatic matching or specific key columns.

  4. 4

    Run the comparison in your browser.

  5. 5

    Review and export the differences.

What this tool will detect

  • Added rows
  • Removed rows
  • Changed values
  • Duplicate keys

Worked example

See exactly what changed between two CSV files.

A stable customer ID connects each row. Nablyx then separates changed, added, and removed records without hiding the source values.

Original CSV

customer_idplanstatus
1001starteractive
1002proactive
1004proactive

Updated CSV

customer_idplanstatus
1001proactive
1002proactive
1006proactive

Highlighted result

Changed rows
1
Added rows
1
Removed rows
1

Accurate comparisons, even with messy CSVs.

Quoted values, multilingual text, and imperfect exports are handled deliberately—not guessed.

Choose a stable row key
Use an ID, SKU, or email that is present once per file. Empty or duplicate keys stop the comparison so rows are never matched ambiguously.
Quoted values are supported
Commas, line breaks, and double quotes inside quoted CSV fields are parsed according to standard CSV escaping rules.
Save files as UTF-8
UTF-8 preserves multilingual names and symbols consistently. A UTF-8 byte-order mark in the first header is handled automatically.

Common uses

  • CRM exports
  • E-commerce catalog data
  • Database exports
  • Accounting data
Privacy by design

CSV parsing and comparison run inside your browser. Nablyx does not upload these files to a server.

How will rows be matched?

Choose a column that exists in both files and contains one unique value per row, such as customer_id, SKU, or email.

Related guide

How to compare two CSV files by key column, step by step

Related tools

Continue with a related Nablyx tool.

Ready to compare your files?

Return to the workspace and review the differences locally in your browser.

Compare CSV files