Compare two spreadsheets, cell by cell

How it works

1. Drop the old version on one side and the new version on the other. Files are read in this browser tab and never uploaded, up to 150 MB each.
2. Pick the column that identifies a row — an order number, an employee ID, a SKU. Comparing two spreadsheets by position tells you almost nothing once a row has been inserted or sorted differently; comparing them by key tells you what actually changed.
3. Read the result. Every record is sorted into matched, changed, added, removed or duplicate, and changed rows show the old and new value side by side for each cell that moved.
4. Filter to one category, search within the result, and narrow the columns to only those that differ when a wide file makes the change hard to find.

Every row lands in one of five categories

The comparison does not produce a list of differences; it sorts every record on both sides into exactly one of these, using the column you picked as the key. The counts add up to the rows you loaded, so nothing is silently dropped.

Matched

The key appears on both sides and every compared cell is identical. These are the rows you do not have to look at, and on a healthy comparison they are nearly all of them - which is the point, because the job is finding the handful that are not.

Changed

The key appears on both sides but at least one cell differs. Each differing cell is shown with its previous value beside the new one, so the question is never "something moved" but "this figure was 1,240 and is now 1,420".

Added

The key is on the right-hand side only. Usually a genuinely new record, but it is also what a re-keyed identifier looks like: change a reference and the same row leaves as removed and returns as added, which is worth checking before treating a large added count as growth.

Removed

The key is on the left-hand side only. A record that was there last period and is not there now - a leaver, a cancelled line, a row dropped by a filter that was left switched on when the export ran.

Duplicate

The same key appears more than once on one side. This is reported separately rather than folded into the others because a duplicated key makes the comparison ambiguous: there is no single row to compare against, so totals built on that key are unreliable until it is resolved.

Choosing the key column is the one judgement the tool cannot make for you. Pick a column that identifies a record and does not change between the two files - a reference, a code, an ID. Pick something that varies, such as a name or a date, and rows that are really the same record will be reported as one removed and one added.

Questions

Are my files uploaded anywhere?

No. The comparison runs entirely inside this browser tab. Nothing is sent to a server, and closing the tab discards everything that was loaded.

Which file formats work?

CSV and XLSX. Legacy .xls files are not read — open one in Excel or LibreOffice and save it as .xlsx or .csv first.

What if the two files have different columns?

Columns present in only one file are named in the result rather than silently ignored, and the comparison runs across the columns the two files share.

What happens if the key column has repeats?

Those records are reported as duplicates rather than guessed at. A key that appears more than once on either side cannot be matched to a single row, so the tool says so instead of pairing them arbitrarily.

Can I download the result?

Comparing and reading the result on screen is free. Downloading it as CSV or Excel is a one-time unlock, shown beneath the export buttons once you have a result.