Detect Changes Between Two CSV Files

Find new, deleted and edited rows between two CSV files, cell by cell, matched by a key column. Free, and your files stay in your browser.

Quick answer: Compare two datasets and see what was added, removed or changed.

How to use the Detect Changes Between Two CSV Files

Compare two datasets and see what was added, removed or changed.

Data Comparison shows exactly what changed between two versions of a file. Pick a key column, or use the first column or the first two columns, and it lists rows that were added, removed or changed, down to the cell. Use it to check an export against last month, to review a data migration, or to find which values a script changed. CSV and Excel are supported.

Load dataset A and B
Pick or type the key column
Review and download the differences

Tips

A key column (like id) matches the same record in both files. Click Use first column as key, pick columns, or type their names.
If you choose no key, the first two columns of the files are used as the key.
Numbers match by value, so 36 and 36.0 are treated as equal.
Use “Ignore case” or “Ignore spaces” to skip trivial differences.

Example

Input: old.csv + new.csv, key = id

Output: 3 new · 2 deleted · 5 edited

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Who uses Data Utility

Frequently asked questions · Data format benchmark

Frequently asked questions

How do I detect changes between two CSV files?

Load the old and the new file, choose a key column that identifies each row, and the tool lists the new, deleted and edited rows, cell by cell.

Can it ignore small differences?

Yes. Turn on Ignore case or Ignore spaces, and set a tolerance so 36 and 36.0 or tiny rounding differences are not reported.

Can the files be different formats?

Yes. A can be a CSV and B an Excel file. Columns are matched by name. JSON and Parquet files are not supported here, so convert them to CSV first.

Can Data Comparison do change data capture (CDC)?

It does the snapshot version of CDC for files. Compare the earlier and the latest export by key: added rows are inserts, changed rows are updates and removed rows are deletes. It does not read database logs or run in real time.

How does Data Comparison find differences?

It matches rows by a key column, or by the first two columns, and shows which rows were added, removed or changed, down to the cell. It works with CSV and Excel files.

Data Comparison (CSV and Excel Diff): Compare two CSV or Excel files by a key column. See inserts, updates and deletes like change data capture (CDC), cell by cell. Free, in your browser.
Compare Two CSV Files: Compare two CSV or Excel files by a key column and see added, removed and changed rows. Free, runs in your browser.
Compare Two Excel Files: Compare two Excel (.xlsx) files by a key column and see every added, removed and changed row and cell. Free, and your files stay in your browser.
CSV Diff Tool: Find the differences between two CSV files online: which rows were added, removed or changed, cell by cell. Free, in your browser.
CDC for CSV and Excel Files (Change Data Capture): Change data capture for files: compare two CSV or Excel snapshots and list inserts, updates and deletes by key. Free, private, runs in your browser.
Find New, Updated and Deleted Rows Between Two Files: List the new, updated and deleted rows between two CSV or Excel files by key and download the differences. Free and private.
Data Reconciliation Tool for CSV and Excel: Reconcile two files: matched records, records missing on either side and values that differ, with a tolerance. Free, in your browser.

Topic guides

CSV Guides and Free CSV Tools