Compare CSV Files
Compare two CSV files online. Match rows by key column, highlight changed cells, and ignore noise like spacing or case. Your data never leaves the browser.
Files never leave your browser.
About CSV Diff
Compares two CSV files row-by-row, key-column aware, ignoring formatting choices. Handles quoted fields, escaped commas, and ragged rows safely.
How to use
- Paste or load both CSV files.
- Choose Key columns under Options to match rows by identifier instead of row order.
- Toggle Trim cells and Ignore case to suppress noise from incidental formatting.
Try a sample
A product catalog with price and stock edits. A typical CSV diff case.
What this tool doesn't handle
- Numeric formatting differences (1,000 vs 1000) are treated as different unless you normalize cells first.
- CSV without a header row requires Has header turned off. Otherwise the first row is treated as labels.
Frequently asked questions
Do my files ever leave my browser?
No. Every comparison runs locally in your browser. Nothing you paste, drop, or load is uploaded to a server; the tool keeps working even if you go offline after the page loads.
Is this tool free to use?
Yes. All DiffResolver tools are free, with no account, sign-up, or installation. Because processing happens on your device, there are no server-imposed usage limits.
How do I compare CSV files where the row order changed?
Set Key columns under Options to one or more identifier columns. Rows are then matched by key instead of position, so reordered rows compare cleanly and real edits stand out.
Can I compare CSV files with different delimiters?
Yes. The delimiter is auto-detected by default and can be set explicitly under Options. For tab-separated data there is a dedicated TSV Diff tool.
What do the Added, Removed, and Changed row statuses mean?
Added rows exist only in the right file, Removed only in the left, and Changed rows share a key but differ in at least one cell. Unchanged rows can be shown for context with Show unchanged rows.
Is there a file size limit?
No server limit applies, because nothing is uploaded. The memory of your device sets the practical limit. Above 10 MB for text, 40 MB for images, 100 MB for documents, or 500 MB for archives, the tool warns you that the work can be slow, but it never blocks the file.
Does this tool work offline?
Yes. The browser keeps a copy of the tool after the first visit, so a page you opened before still works without a network. You can also install DiffResolver as an app from the browser menu. Installation stays optional; the site works the same in a normal tab.
Where is my data stored?
Your files are stored nowhere. They stay in the memory of the page and are gone when you close the tab. Only what you save yourself stays in this browser: a snapshot, your tool options, and your theme. To remove it, open Settings and select Clear all local data.