Compare CSV Files
Free CSV compare tool. Diff two CSV files by key column or row, see added, removed and changed rows with cell highlights and export the differences. Private.
- No upload — 100% private
- Instant, on your device
- Free, no sign-up
- Works offline once loaded
How it works
How to use Compare CSV Files
Drop the original file as File A and the newer file as File B, or try the sample files.
Keep the suggested key column (such as id or email) or pick your own — or compare row by row.
Check the column mapping if the headers differ, and choose whether to ignore case and extra whitespace.
Filter the added, removed and changed rows, then download the differences as a CSV.
Why use it
Why use our Compare CSV Files tool
Match rows by key
Rows are paired by one or more key columns, so a re-sorted export still compares correctly. Unique, id-like columns are suggested automatically.
Cell-level highlights
Changed rows show exactly which cells differ, with the old value struck through next to the new one.
Column mapping
Headers that differ only in case or spacing are matched automatically, and you can map renamed columns by hand or leave columns out.
Fast on big files
Comparison runs in a background worker using hash maps, so files with 100,000 rows are diffed in moments.
Export the differences
Download a CSV listing every added, removed and changed row with its row numbers and the changed columns.
Private and offline
Both files stay on your device — nothing is uploaded, so it is safe for customer, payroll and financial data.
FAQ
Frequently asked questions
How do I compare two CSV files?
Drop the older file as File A and the newer one as File B. The tool pairs rows by a key column, then lists rows that were added to B, removed from A, or changed, with the changed cells highlighted.
What is a key column?
A column that identifies a record, such as id, SKU or email. Pairing rows by key means the comparison still works when rows are sorted differently. Pick several key columns if no single column is unique.
What if the files have no key column?
Choose Row position to compare row 1 with row 1, row 2 with row 2 and so on. This works best when both files are in the same order.
Can I compare files whose column names differ?
Yes. Open Column mapping and choose, for every column in File A, the matching column in File B — or don’t compare it. Names that differ only by case or spaces are matched for you.
Can I ignore differences in case or spacing?
Yes. Ignore case treats “ADA@example.com” and “ada@example.com” as equal, and Ignore extra whitespace ignores leading, trailing and repeated spaces.
Are my CSV files uploaded?
No. Both files are read and compared in your browser. Nothing is sent to a server.
Related tools
Diff Checker
Compare two texts side by side with word-level highlights.
CSV Cleaner
Dedupe, trim, fix and sort messy CSV data.
Merge CSV Files
Combine many CSV files into one, matched by header.
CSV to JSON Converter
Convert CSV to JSON and JSON back to CSV, privately.
JSON Formatter
Beautify, validate, minify and explore JSON as a tree.
Base64 Encode & Decode
Encode or decode Base64 text, files, images and data URIs.
URL Encode & Decode
Percent-encode, decode and edit URL query parameters.
Hash Generator
MD5, SHA-1, SHA-256, SHA-512 and HMAC for text or files.