Compare two Parquet files — privately, in your browser
To compare two Parquet files, drop both into Diffesq: it shows a three-layer diff — schema changes, per-column statistics, and key-matched row differences — without uploading either file. Rows are matched on a key column (auto-suggested, e.g. an *_id column), so a reordered file with identical data reports zero changes.
Because everything runs locally, it works for the datasets you can't send to a SaaS diff tool: production extracts, customer records, financial actuals. You can also compare a Parquet file against a CSV — columns are matched by name and compared on a common type.
How it works
- Open the Diffesq workbench and drop a .parquet file on each side.
- Diffesq reads the schema from each file's footer, then compares columns, per-column statistics, and key-matched rows on your device.
- Review the three layers — schema, profile, rows — and adjust the key, numeric tolerance, or ignored columns; every change recomputes locally.
What the comparison covers
- Schema diff: columns added, removed, retyped, reordered; nullability changes.
- Profile diff: row counts, null rates, distinct counts, min/max, mean and standard deviation per column, with changed metrics flagged.
- Key-matched row diff with composite keys, absolute/relative numeric tolerance, ignore-case, trim, and ignore-column options.
- Cross-format comparison against CSV, SQLite, JSON Lines, and Arrow files.
- Large files degrade gracefully: past ~2 million cells the row diff samples; past ~20 million it steps aside while schema and profile still cover the full dataset.
- Exports: Markdown/JSON reports, changed rows as CSV, and the schema diff as text.
Free vs Pro
Structured-file comparisons run in full on your device on the free tier, with about a third of the results shown as a preview; Pro unlocks the complete results and clean, unwatermarked exports (HTML, Markdown, JSON, PDF).
See Pricing for plans — $6/month, $48/year, or $119 once.
Privacy
Every comparison runs locally in your browser. Your files are never uploaded — there is no server that receives them, and the page keeps working with Wi-Fi turned off. Details in the Privacy Policy.
Frequently asked questions
Which Parquet features are supported?
Standard row groups with Snappy, gzip, Brotli or zstd pages. Encrypted-footer files and exotic encodings are rejected with a specific message rather than a wrong answer.
Do I need an account?
No. Comparisons run without any signup. Pro features unlock with a license key — still no account or login.
Does it work offline?
Yes — once the page has loaded, parsing, comparing, and rendering all happen on your device. Turn off Wi-Fi and it still works.