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CSV Merge & Reconciliation

Merge CSV files with an exact file-by-column review, source-row quarantine, and no automatic header matching.

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Data handling

Storage and export controls

Retention
The tool's working state is kept only while this page is open. Inputs and results are not saved to persistent storage by Got A Tool.
Export
The tool may prepare a result after you run it. It downloads or copies it only when you choose that action.

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How it works

Merge CSV files without silently matching their headers.

01

Choose files and file settings

Select two to twenty CSV files, then choose the delimiter and encoding that match the source files.

02

Choose a column rule

Keep the union of exact headers, or deliberately keep only headers every file shares.

03

Review the ZIP contents

Download merged rows, a per-file report, and a quarantine CSV whenever source rows need review.

Choose a column rule

Keep every exact header, or intentionally reduce the output.

Union of columns

Use this default when files have different fields and you need every exact header in the merged CSV. Missing values stay blank.

Shared columns only

Use this only when every output row must contain the same exact headers. Columns missing from any file are excluded and listed before download.

Similar-looking headers such as Email and email remain separate. The tool never guesses that they mean the same thing.

Continue the workflow

Use the next tool for the next data task.

Does the tool automatically match similar columns?

No. Header names remain exact. Similar-looking names are surfaced as a warning instead of being silently combined.

What happens to malformed source rows?

Rows with quote or column-count issues stay out of merged.csv and appear in quarantine.csv with their source file, source row, reason, and original text.

What is in the download ZIP?

The ZIP contains merged.csv and report.csv. It also includes quarantine.csv when one or more source rows need review.

Are formula-like cells protected?

Formula protection is on by default. It adds an apostrophe before cells that begin with a spreadsheet formula trigger; you can turn it off before reviewing the files.

Are my files uploaded?

No. File reading, column review, merging, and ZIP creation happen in your browser.

Practical guide

Read the Change-review checklist

Choose the comparison that matches the file, inspect the reported differences, and keep the source until the reviewed copy is ready to use.

Open the guide →

Keep working

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