Compare two CSV files by one exact key.

Paste two small comma-delimited CSV files. Choose a shared key column, then find missing keys and changed values in shared columns. Everything stays in this browser tab.

Earlier or reference CSV

Later or comparison CSV

Exact key column

Nothing is uploaded. Paste only data you are allowed to process.

Matched—

Changed—

Left only—

Right only—

Rules: the key must be present, nonempty and unique in each file. Matching is exact and case-sensitive. The checker compares only columns present in both files. It preserves leading zeros as text and does not infer fuzzy matches or business meaning.

Limits: each pasted CSV may contain up to 10,000 data records, 100 columns and 5 MB of UTF-8 text. The tool does not change either source. Review the report before relying on it for accounting, inventory or payment decisions.

Need a reproducible reconciliation package?

The fixed USD 29 service returns unmatched-key CSVs, a changed-cell CSV, a JSON report with source hashes and the Python script used for the comparison.

Review the USD 29 scope Download version 1.0.0 Support this free checker

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