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CSV Diff Checker
Compare an old and a new version of a CSV file. Rows are matched by a key column such as an ID or email, so you see exactly which rows were added, which were removed and which cells changed, even when the rows are in a different order.
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Both files are compared in your browser and never uploaded.
added rowremoved rowchanged rowold value → new value
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How to use the CSV Diff Checker
- Add the original CSV on the left and the changed CSV on the right (open the files or paste the data).
- Check the key column: a unique column such as id or email is picked automatically. Choose another one, or Row position for files without an ID.
- Set the comparison rules: ignore case, spaces or number formatting, or exclude a column such as a timestamp.
- Review the differences: the counters summarise the changes and the table highlights every changed cell.
- Download the diff CSV or the cell-change log to share or archive the result.
How rows are matched
| Situation | Match by key column | Match by row position |
|---|---|---|
| A row was inserted in the middle | Reported as 1 added row | Every following row looks changed |
| The file was re-sorted | No differences (rows are found by key) | Most rows look changed |
| Files have no ID column | Use another unique column (email, SKU) | Works well if order is stable |
| A value in an existing row changed | 1 changed row, changed cell highlighted | 1 changed row, changed cell highlighted |
Reading the result
- Added (green): the key exists only in the changed file.
- Removed (red, struck through): the key exists only in the original file.
- Changed (yellow): the key exists in both files but at least one compared cell differs; the old value is crossed out and the new value is shown next to it. The small badge on a column header counts the changed cells in that column.
- Column headers in dark green exist only in the changed file; dark red ones only in the original. Their values are shown but not counted as cell changes.
Comparing JSON instead? Use JSON Compare. To check two plain text files line by line, use Text Compare.
Frequently asked questions
How do I compare two CSV files?
Open or paste the original file on the left and the new file on the right. The comparison runs immediately: added rows are green, removed rows are red, and changed cells show the old value crossed out next to the new value.
What is a key column and why does it matter?
A key column uniquely identifies each record, such as an ID, SKU or email address. Matching by key means a row is compared with the row that has the same key in the other file, so sorting differences or inserted rows don't cause false changes. Without a key, rows are matched by position.
Does the column order have to be the same?
No. Columns are matched by their header names, so files with reordered columns compare correctly. Columns that exist in only one file are shown and counted as new or dropped columns.
Can I ignore small differences like capital letters or trailing spaces?
Yes. Tick Ignore upper/lower case, Ignore spaces at the ends, or Treat equal numbers as equal (so 5, 5.0 and 5.00 match). You can also exclude one column, such as last_updated, from the comparison.
What does the exported diff CSV contain?
One row per added, removed or changed record, with a change column, all values (new values, or old ones for removed rows), a list of the changed columns and the previous values of every changed column. The cell-changes export lists each changed cell as key, column, old value and new value.
What if my key column has duplicate values?
Repeated keys are paired in the order they appear and a warning is shown. For exact results choose a column whose values are unique in both files.
Are my files uploaded?
No. Both CSV files are read and compared locally in your browser; nothing is sent to a server.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.
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