See exactly what changed between two lists
Choose a unique key to find missing rows, extra rows, and different values under the same ID.
1. Choose two CSV files
Each file: up to 1 MiB, 5,000 data rows, and 30 columns. UTF-8, comma-separated CSV with a header row only.
2. Confirm the column mapping
Load both CSV files to select the unique key and the fields to compare.
Columns with identical names are suggested for comparison. Check every pair. Column names can differ; each side may use a column only once per list.
Choose two CSV files to start.
Fix this before reconciling
3. Review all four categories
Reconcile the files to see counts, source data-row numbers, and complete differences here.
Data-row numbers start at 1 after the header. Expand long values to read them. Downloads retain all content.
The two UTF-8 reports may total up to 16 MiB. Exceeding the limit disables both downloads; page results remain readable. Reports contain source values; store them carefully.
Files are processed in this page
No account, file upload, browser storage, or telemetry. Clearing or leaving releases page references and download links. It does not delete files you downloaded or guarantee secure memory erasure.
Before you start
Will it treat 001 and 1 as the same key?
No. Values are compared as exact strings by default.
Do I need to upload my files to an account?
No. The page processes selected files in memory.
What happens when a key is duplicated?
Reconciliation stops and identifies the conflicting rows; it never guesses a pairing.