Compare Two CSV Files Online
Drop two CSV or JSON files and see exactly what changed — row by row, cell by cell. Match rows by a key column, resolve conflicts, and export the merged result. 100% in your browser: no upload, no sign-in, no data ever leaves the tab.
Add two files to compare.
Compare CSV files by key, not row position
Pick the column that uniquely identifies each row — id, email, SKU — and the diff lines up matching rows even if one file is re-sorted, filtered, or has rows in a different order. Auto-detect suggests a likely key on drop.
A cell-level diff, not a line-level one
Generic text diff tools compare lines as strings and break the moment a column is reordered. This diff understands the table: it reports exactly which cell in which row changed, and leaves untouched cells alone.
Everything you need to compare, in one tab.
Drop two files and see exactly what changed — cell-level diff, key-based row matching, one-click conflict resolution, an AI summary, and a merged export. Nothing is uploaded.
Three steps, zero setup.
Guides & insights.
Practical walkthroughs on comparing CSV files online — from picking the right match key to validating data migrations.
Frequently asked questions
How do I compare two CSV files online?+
Drop both files into the panel above, choose the column that uniquely identifies each row (the match key), and read the colour-coded result: modified, added, and removed rows. The whole comparison runs in your browser and takes a few seconds.
Is my data uploaded anywhere?+
No. The tool is 100% client-side — files are parsed and diffed entirely in your browser tab and never sent to a server. That is what makes it safe for sensitive data such as PII, financial records, or health information.
What is a match key?+
A match key is the column (or combination of columns) that uniquely identifies each row — for example customer_id, email, or SKU. The diff engine uses it to line up the same record across both files, so reordered or re-sorted exports still compare correctly.
Can I compare JSON files too?+
Yes. JSON arrays are flattened into a tabular view for the diff and rebuilt with proper types on export, so you can compare JSON against JSON — or even CSV against JSON when the columns line up.
How large a file can I compare?+
Comfortably up to roughly 50,000–100,000 rows on a typical laptop. The table is virtualised so scrolling stays smooth; very large files (millions of rows) are better handled by a command-line tool.
Is it free?+
Yes — the tool is free with no account or sign-in. There is no server to run, so there is nothing to meter. Optional AI features use your own provider key, which most providers offer with a free tier.