Compare one column across two tables, matched by key
Paste two CSVs, pick a key column and one value column, and get a clean list of every key whose value changed — old → new — ignoring all the other columns. Runs entirely in your browser, no upload.
What this tool does
Column Value Diff joins two tables on a key column and compares a single
value column between the matched rows — reporting every key whose value changed as a
clean old → new pair. Every other column is ignored, so two exports with different
surrounding columns still reconcile cleanly on the one metric you care about: a price, a
quantity, a status, a balance.
It's the focused answer to "did the value for this id change between yesterday's file and today's?" — where a full cell-by-cell diff would drown you in unrelated column noise.
Worked example
Original CSV
id,name,price
1,Apple,10
2,Banana,20
3,Cherry,30
Updated CSV
id,name,price
1,Apple,12
2,Banana,20
3,Cherry,35
With key = id and value = price, the table report is:
value column "price" · 3 keys matched · 2 changed · 1 unchanged
~ [1] "10" → "12"
~ [3] "30" → "35"
Row 2 (Banana) is unchanged, and the name column is never compared. Switch the output
to CSV change-log for a flat, pasteable result:
key,status,old,new
1,changed,10,12
3,changed,30,35
Turn on Include keys on only one side to also list keys that appear in just one file
(left_only / right_only) — useful for spotting added or dropped rows alongside the value
changes.
How to use it
- Paste the original (old) CSV and the updated (new) CSV.
- Enter the key column(s) that identify a row — e.g.
id, orfirst,lastfor a composite key. Reordered rows still match, because rows are joined by key, not by line. - Enter the value column to compare — the one metric, e.g.
price. - Pick the delimiter, header, and matching options, then read the
old → newreport.
Everything runs locally in your browser — the CSVs are never uploaded.
FAQ
How is this different from a full CSV diff?
A full cell diff compares every column and flags every changed cell, plus whole columns
that were added or removed. That's noisy when the two files have different surrounding
columns. This tool compares one value column, matched by key, so you get just the
key → old/new changes for the metric you care about — nothing else.
Can I match on more than one column?
Yes. Enter a composite key as a comma-separated list, e.g. first,last or
store,sku. Rows match only when every key column agrees. Duplicate keys are paired in
their original order.
What if a key exists in only one of the files?
By default those rows are ignored, so the report shows only value changes for keys present
in both tables. Turn on Include keys on only one side to also list them as
left-only (only in the original) and right-only (only in the updated) with their value.
My CSV has no header row — can I still use it?
Yes. Turn off First row is a header and reference the key and value columns by their
1-based index instead of a name — e.g. key 1, value 3. Columns are labelled
col1, col2, … internally.
Does it treat "10" and "10.0" (or different case) as equal?
Values are compared as text, so 10 and 10.0 are different, and Yes differs from
yes unless you enable Ignore case. Enable Ignore whitespace to fold runs of spaces
(so in stock matches in stock). Both options affect matching only — the report always
shows the original text.
Limits & edge cases
- Comparison is textual — there's no numeric tolerance or rounding;
10≠10.0. - The key and value columns are required and must exist in both tables (by name, or by 1-based index when header is off), otherwise you get a clear "not found" error.
- Duplicate keys pair in order (1st-with-1st, 2nd-with-2nd); leftover duplicates on one side surface as unmatched when Include keys on only one side is on.
- Supported delimiters: comma, tab, semicolon, pipe, or any single character. Quoted fields and embedded commas/newlines are parsed correctly.
- Processing is entirely in-browser (wasm); large files are handled in memory with no upload.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool column-value-diff "id,name,price
1,Apple,10
2,Banana,20
3,Cherry,30" 'right=id,name,price
1,Apple,12
2,Banana,20
3,Cherry,35' 'key=id' 'value=price'New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/column-value-diff/?left=id%2Cname%2Cprice%0A1%2CApple%2C10%0A2%2CBanana%2C20%0A3%2CCherry%2C30&right=id%2Cname%2Cprice%0A1%2CApple%2C12%0A2%2CBanana%2C20%0A3%2CCherry%2C35&key=id&value=price&delimiter=comma&header=true&ignore_case=true&ignore_whitespace=true&include_unmatched=true&format=tableMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.