What is CSV comparison?
It compares records in two comma-separated files to find new records, removed records, changed field values, and records that are unchanged. CSV Change Tracker uses the key columns you select to identify records.
FAQ
Questions, answered.
Answers about CSV comparison, local file privacy, matching fields, duplicate IDs, CSV exports, and browser limits.
How does CSV Change Tracker work?
Select old and new files, choose one or more matching columns, and click Compare files. A local browser Worker runs the same shared comparison engine used by the Chrome extension.
Are my files uploaded to a server?
No. The application reads files only after you select or drop them. Parsing, comparison, filtering, and CSV generation happen locally. Hosting still serves the website and may log ordinary page requests.
Can I compare large CSV files?
This build accepts up to 20 MiB per file and protects the browser with a combined 2,000,000-cell budget and 10,000-column budget. Limits protect memory; they are not paid quotas. Very wide records and long fields can use more memory. Use Cancel operation to stop processing.
Can I compare files without an ID column?
Yes. Select multiple fields as a joint key. Every component must be non-blank, and the combination must be unique in each file. The tool does not guess which duplicate records belong together.
What happens if the files have different columns?
Columns with exactly matching header names are aligned regardless of order. Added and removed columns are listed as structure changes; missing and empty values remain distinct. If there is no shared key column, comparison cannot proceed.
What if my CSV has no header?
Uncheck First row contains headers before comparing. The tool generates Column 1, Column 2, and so on. Both files then need the same column order. It cannot infer reordered columns without headers.
What happens with duplicate or blank IDs?
Comparison stops and lists affected records. Fix the source data or choose additional matching fields. The tool never overwrites duplicates or silently discards affected records.
Can I export comparison results?
Yes. Export All changes, Added rows, Removed rows, Modified rows, or Summary. Exports include the full selected category, regardless of the table filter or page. CSV preserves source values. When opening reports in spreadsheet apps, import as text if cells could be interpreted as formulas.
Is the tool free?
Yes. This version is free, with no registration, login, payment, or license key.
Can I use Excel or non-UTF-8 files?
Not in this version. Save Excel workbooks as UTF-8 CSV first. GBK and UTF-16 are not supported, and invalid UTF-8 produces an error rather than silently changing your data.