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Compare Two CSV Files

Match rows by a key column and find added, removed and changed records.

Each file: 10 MiB raw and 5,000,000 text units. Both files together: 2,000,000 parsed cells.

File A — Before

Separator

Encoding

File B — After

Separator

Encoding

Match by key

Keys match as exact text. Case, spaces and leading zeros matter.

Key in A

Key in B

How to compare CSV files

  1. Paste or open the before and after files.
  2. Choose a key column on each side and the value columns to compare.
  3. Review differences and unresolved rows; download the full report.

What the comparison shows

  • Matches records by exact key, regardless of row order.
  • Shows duplicate keys separately instead of guessing.
  • Exports complete JSON and CSV reports.
  • Compares only the selected value columns and lists schema differences separately.

When this is useful

  • Check changes between inventory exports.
  • Compare reports with reordered columns.
  • Audit changed prices in recurring supplier files.

How to read the results

Added means only in B; removed means only in A. A changed key appears as a removal and an addition.

One-sided columns are schema differences; excluded fields limit equality.

Reading the CSV record report

The CSV report uses fixed field names: status, key_before, key_after, row_before, row_after, before_present, after_present, changed_columns, before_values, after_values, reason. Source record numbers are 1-based and include the header record.

The statuses added, removed, changed, unchanged and unresolved are stable codes. changed_columns and the values fields contain JSON arrays; a missing side is JSON null. The JSON report also includes settings, column mappings and counts.

Privacy and limits

Files are parsed in your browser. Each may be 10 MiB raw and 5 million text units; together they may contain 2 million cells.

CSV comparison questions

No. Records are matched by the key you choose.

Every related row is unresolved and included in the report.

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