Big CSV viewer

Open and query CSV files that are too big for Excel — with real SQL, in your browser.

🔗 Live tool →

Why

Excel stops at 1,048,576 rows. Google Sheets stops much earlier. Most "online CSV viewers" want to upload your data first, which is a non-starter for anything real.

Drop the file here instead. It opens in seconds, and you get a SQL prompt.

Features

• Handles files of several hundred MB — the data is streamed off your disk, never loaded into the DOM
• Full DuckDB SQL: joins, window functions, SUMMARIZE, USING SAMPLE
• Also reads TSV, JSON / NDJSON and Parquet
• Column list with inferred types, click to insert into your query
• Export the query result back out as CSV
• ⌘/Ctrl + Enter to run

How it works

DuckDB-WASM registered against a BROWSER_FILEREADER file handle, so DuckDB reads ranges directly from the File object on disk rather than materialising the whole thing in memory. Your file is exposed as the table t.

Examples

SELECT * FROM t LIMIT 100;
SUMMARIZE t;
SELECT country, count(*) AS n, avg(amount) AS avg_amount
FROM t GROUP BY country ORDER BY n DESC;

Run it yourself

python3 -m http.server 8000

Licence

MIT