FOR RECURRING EXPORT CHECKS
Same records.
What changed?
Match two CSV files by ID, check the fields that matter, and take away a clear report. Row order doesn’t matter.
The earlier version or your source of truth.
The newer version or the system you’re checking.
Choose a stable, unique ID. Duplicate and blank IDs are flagged, not silently merged. The web tool uses one key; the batch toolkit supports composite keys.
Fields to check
Map each selected A column to its B counterpart.Numeric comparisons use exact plain decimals. Currency symbols, thousands separators, scientific notation and blank values are flagged as invalid. Text fields and IDs keep leading zeros.
| Status | Key | A / B records | What changed |
|---|
A SIMPLE CHECK, WITH GUARDRAILS
Check the data.
Keep the context.
- Start with two exports. A CRM migration, weekly inventory sync, or two versions of a customer table. The tool compares records, not lines.
- Choose the ID and fields. Ignore columns you expect to change. Map renamed headers. Apply numeric tolerance only where it makes sense.
- Review the exceptions. Inspect changed fields, missing IDs, duplicates and invalid values before treating anything as a match.
- Keep a report and settings. Download HTML for review or CSV for further work. Save a settings file for next time; it contains column names and rules, not rows.
FOR CHECKS YOU RUN AGAIN
From a one-off check
to a repeatable workflow.
The offline batch toolkit adds a Node command-line runner, composite keys, saved JSON rules, a sample migration check, and a walkthrough you can keep with your project.
Use it on your machine or in an existing CI setup. No API keys, database or paid runtime service is required.
Before you compare
Does this upload my files?
The comparison runs in your browser. The app makes no requests to send CSV data and does not save it to browser storage. The hosting provider may keep normal page-access logs. Downloads contain the data you choose to export; store them carefully.
What happens with duplicate IDs?
An ID present more than once on either side is marked ambiguous. The group counts as one flagged key, and the report lists its data record numbers. It is excluded from changed and unchanged counts. Fix the duplicate or use composite keys in the batch runner.
Can I compare spreadsheets or very large files?
This version supports UTF-8 CSV/TSV, up to 2 MB and 20,000 data rows per input in the web tool. Export one sheet as CSV first. The batch runner has a 10 MB / 200,000-row limit per input. It loads files into memory and is not a streaming engine.
Is this an accounting reconciliation system?
No. It compares data values and reports exceptions. It does not establish correct totals, settlement status, tax treatment or a financial sign-off. Review important changes in the original systems.
Follow a worked free exercise
Compare repeated CSV exports when row order and IDs need separate checks. Run synthetic proof and download the sample.