KeyDiffCompare two CSV exports by key. Offline.
KeyDiff is a single HTML file that finds added, removed and changed rows between two CSV exports — by key column, including composite keys, ignored columns and numeric tolerance. Files are processed in your browser; the page cannot call the network (CSP connect-src 'none').
One payment · no account · no subscription · download delivered by email after manual payment check
What it does
Keyed add / remove / change
Match rows by one or more key columns. See which keys appeared, disappeared or changed cell by cell.
Messy real-world CSV
Auto-detects comma, semicolon, tab or pipe. Handles quoted fields, UTF-8 BOM, reordered columns and added/removed columns.
Tolerance and ignore list
Treat 40 and 40.004 as equal with a numeric tolerance. Ignore volatile columns like updated_at.
Diff CSV export
Download status,key,column,old_value,new_value for every difference, not only the on-screen preview.
Real sample preview
From the free sample pack (key = id, tolerance = 0.01). This is the start of the actual expected report file, not a mock-up:
| status | key | column | old | new |
|---|---|---|---|---|
status | key | column | old_value | new_value |
removed | 3 | | | |
added | 5 | | | |
changed | 2 | email | ben@x.com | BEN@x.com |
changed | 2 | balance | 20 | 25 |
Open the demo and upload the free sample CSVs to reproduce this report on your computer. Processing stays in the browser.
# Free sample pack
old.csv / new.csv / expected-report.csv
# Demo steps
1. Open /demo/
2. Old = old.csv, New = new.csv
3. Key = id · Tolerance = 0.01
4. Compare → Download diff CSVLimits (honest)
- Both files are held in browser memory. Comfortable roughly up to 100k–300k rows depending on your computer.
- On-screen table shows the first 2,000 rows per status; the downloaded CSV has all differences.
- Values are compared as text unless you set a numeric tolerance.
- Tested in headless Chrome for the v1.0.0 release. Firefox/Safari/mobile browsers should work for typical files but were not part of that automated suite.
- Free online alternatives and open-source CLI tools exist. KeyDiff’s angle is a single offline file with CSP-enforced zero network and a simple one-time purchase.
Price
$9 once in USD. Public competitor prices checked on 2026-11-05 included Lake3Tools CSV Compare at $49 (one-time), Sobolsoft CSV Compare at $19.99, and VImplement CSV Compare Individual at NOK 799. KeyDiff is a simpler browser HTML tool, so $9 sits below that paid range. Free tools also exist; this purchase is optional ownership of the offline file, samples, source and tests.
No revenue claims, discounts, scarcity timers or review badges on this site.
Questions
Does my CSV leave my computer?
No. The File API reads the file into memory in your browser. The demo and the paid HTML both ship with Content-Security-Policy connect-src 'none', so the page cannot open network connections. No analytics scripts are included.
What do I get after paying?
A ZIP with keydiff.html, sample CSVs, LICENSE, README, and the source/tests folder. Delivery is manual: after USDT (TRC20) or PayPal payment and the order email, we send an unlisted download link, usually within 24 hours.
Is income or a result guaranteed?
No. The tool reports differences in the files you give it. It does not guarantee business outcomes, and we do not promise you will earn money by buying it.
Refunds?
If the product does not work as described and we cannot fix it, write within 14 days for a refund. See the terms.