Free, browser-based utilities for everyday developer workflows

CSV Join / Merge / Compare

Compare two CSV snapshots by key, find missing rows, inspect changed columns, and export joined output for QA or analyst workflows.

  • Compare left-only, right-only, matching, changed, and duplicate-key rows.
  • Generate left, inner, or full-outer joined CSV output from two datasets.
  • Useful for reconciling exports, analyst snapshots, and regression test fixtures.

Use cases

Compare Two CSV Exports by ID

Explore more in the Use cases library.

Comparison settings

The key should exist in both CSV files. Use comma-separated keys for composite joins, such as account_id,region.

Left CSV

Right CSV

Summary

Matching keys-
Changed rows-
Left only-
Right only-
Duplicates-

Diff details

Joined CSV output

How to use CSV Join / Merge / Compare

Paste two CSV datasets, enter the shared key column, and run the comparison. The tool highlights missing rows, changed columns, duplicate keys, and generates joined output you can copy into downstream analysis.

Common use cases

Analysts use this to reconcile exports from different systems, QA teams compare expected vs actual datasets after test runs, and developers validate migration scripts against pre- and post-change snapshots.

Why run this in your browser?

All processing happens locally in your browser. Your CSV files stay on your machine, which is useful for customer exports, internal reports, and regression data that should not leave the device.