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Compare Two CSV Files — CSV Reconciliation Studio

Free private CSV comparison and reconciliation tool. Compare two spreadsheets by one or two ID columns, find added, removed and changed records, review cell-level differences, detect duplicate keys and export reports. No upload or signup.

Make it yours

◈ On-device processing
Find what changed, not which line moved.

Compare inventory snapshots, CRM exports, contacts or order lists. Safe key-based matching means sorting is no problem.

01 Add your two datasets

OLDER / ORIGINAL
NEWER / UPDATED

Files are read in your browser, not sent to this application's server. Limit: 3 MB per imported file, 20,000 data records and 100 columns per dataset.

02 Match & reconcile

Ready for two CSV files

Columns to compare (available after your first comparison):

For example, when SKU A001 changes from stock 12 to 14, you'll see one changed record—not a removal and addition. Rows with duplicate IDs are held out for manual review.

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How to use this tool

Upload or paste an older and newer CSV export, then press Compare files. The studio detects comma, semicolon and tab delimiters, displays shared columns and suggests a unique ID such as SKU or email. Optionally choose a second matching key, data fields, trimming, case-insensitive comparison or numeric tolerance. Review added, removed and edited records, then export CSV reports.

Quick steps

  1. Choose an original and updated CSV, or try the example. The files are read only inside your browser.
  2. Compare using a unique primary or composite key, choose fields and review changed cells, additions, removals and key warnings.
  3. Filter the results and download added, removed, changed, full-difference and duplicate-key CSV reports.

Practical tip

Choose a stable, truly unique ID. Row order does not matter, but duplicate or blank IDs are excluded and reported separately instead of silently paired. Fields that exist in only one file are flagged but not compared. CSV is supported, not native XLSX; export Excel or Google Sheets workbooks as UTF-8 CSV first. Files remain within the app's JavaScript memory and are not uploaded by this comparison tool.

Common questions

How can I compare two CSV files when rows are sorted differently?

Choose a unique key column such as SKU, customer ID or email. Matching uses the key, not line number, so reordered rows do not produce false additions or deletions.

Can I compare two columns as a composite key?

Yes. Choose a primary key and an optional second shared column. The pair must be unique in each dataset; blank and duplicate key combinations are excluded with an issues report.

What counts as a changed cell?

For records with the same key, the tool compares selected shared columns. By default it compares exact text; optional trimming, case-insensitivity and an absolute numeric tolerance can reduce harmless differences.

What if the CSV files have different columns?

The tool reports column names present only on one side. Select shared data columns to compare; unmatched columns are not guessed or silently mapped.

Does it support Excel XLSX files?

Not directly. Export each worksheet as UTF-8 CSV and load those files. This ensures a clear comparison of saved values rather than undocumented Excel formula behavior.

Can I download added, removed or changed rows?

Yes. Export added and removed rows in their original column order, changed cells with before and after values, a combined differences report, and a report of blank or duplicate keys.

Does anything get uploaded?

The comparison application reads the files locally in your browser and has no upload endpoint. The website itself can load separate third-party ad content; do not process highly confidential information on an ad-supported webpage without checking your policies.

Is CSV comparison suitable for accounting reconciliation?

It can surface candidate differences in exported records. It does not certify completeness, reconcile amounts across multiple unmatched line items, or replace an independent financial audit. Review any excluded or ambiguous keys.

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Compare CSV files by key, not by row number

A CSV diff is useful when you have two exports of the same customer list, product catalog, stock ledger or order feed. Sorting can make a basic line-by-line comparison useless: the same products might appear in a completely different order. This free CSV reconciliation studio matches records using an identifier such as SKU, order ID or email, then reports actual changes to the fields you choose.

Example: product inventory changed overnight

Suppose yesterday's CSV includes SKU A-001 with 12 units, SKU A-002 with 20 units and SKU A-003 with 7 units. Today A-001 has 14 units, A-002 remains unchanged, A-003 has disappeared, and A-004 is new. With SKU selected as the key, the correct output is one changed, one unchanged, one removed and one added record—regardless of the order of the rows or columns.

How to compare two CSV files online

  1. Export both spreadsheets as UTF-8 CSV. Paste their contents or select CSV files from your device.
  2. Choose Compare files to read the headers and automatically suggest a matching key. You can choose another shared key or add a second key to identify records uniquely.
  3. Choose which shared fields matter. Use trimming or case-insensitive matching for inconsistent exports and numeric tolerance for harmless precision differences.
  4. Compare again and inspect added, removed, changed and unchanged tabs. Search a record by identifier or changed field.
  5. Download the full audit log, changed-cell list, added and removed records, or missing/duplicate key report for follow-up.

What makes a reliable reconciliation?

A stable unique key is essential. If a customer number appears twice in one file, there is no safe automatic way to know which older row belongs to which newer row. This tool deliberately omits ambiguous keys from its matched totals and produces a separate issues report. Likewise, records with empty keys are excluded rather than incorrectly joined together. Differences in column headers are flagged; renamed columns are not assumed to mean the same thing.

This is a comparison of exported values, not a financial certification or an Excel formula interpreter. Dates remain strings; spreadsheet formulas must first be recalculated and exported by the spreadsheet application. Numerical tolerance is an absolute amount, not a percentage. If precise monetary reconciliation matters, leave tolerance at zero and verify values against the authoritative ledger.

Privacy, file formats and accessible exports

The app reads CSV text inside your browser and does not send CSV file contents through an application upload endpoint. It does not keep a cloud copy. Third-party advertising may be loaded by the surrounding site; do not place regulated confidential records into an ad-supported site without independent policy review. Reports are plain CSV, compatible with most spreadsheet software. The printable screen displays an on-page sample; the downloadable data contains all detected records, not just the first 60 shown in the preview.

Frequently asked workflow questions

Can I reconcile two CSV files with different column orders?

Yes. Headers are matched by name and records by unique identifiers. Column order and row order do not affect matching.

What happens if two customers have the same name?

Use a separate unique account ID or a combination of columns. Names alone may not be stable or unique. Duplicate matching keys are excluded and reported separately.

Does it compare Excel workbooks directly?

No. Open the worksheet in Excel, Numbers or Google Sheets and export it as UTF-8 CSV first. This tool does not interpret formulas or workbook formatting.

How do I check a supplier's latest price list?

Use SKU as the key, select price and description as comparison fields, and export changed cells and any newly introduced or discontinued SKUs. Confirm currencies and tax assumptions manually.