Open a CSV file that's too large for Excel

Why Excel can't open your file

Every Excel worksheet is capped at 1,048,576 rows and 16,384 columns. When a CSV is longer than that, Excel shows "File not loaded completely" and silently drops everything past the limit. LibreOffice has the same cap. Google Sheets stops much earlier, at 10 million cells in total.

QueryLocal doesn't use a spreadsheet grid. It loads your file into a real database engine (SQLite, compiled to WebAssembly) that runs inside your browser. A few million rows is routine; the practical limit is your computer's memory, typically somewhere between 500 MB and 1 GB of CSV on a recent laptop.

How to open a large CSV

1. Drop the file on the box above (or click it to browse). A progress bar shows how much has been read.
2. The first rows appear right away. The line above them shows the exact row count, the columns, and the separator that was detected (comma, semicolon, tab or pipe).
3. Use Filter rows to keep only what you need, then Download the result. If it's now under 1,048,576 rows, it will open in Excel normally.

Getting the data back into Excel

Most of the time you don't need all 5 million rows in Excel — you need one region, one year, one customer. Filter first, then download:

SELECT *
FROM data
WHERE country = 'France'
  AND order_date >= '2025-01-01';

Pick CSV for Excel (;) if your Excel uses a comma as decimal separator (French, German, Spanish, Italian… settings): the file is saved with semicolons, decimal commas and a UTF-8 marker so accents display correctly. Otherwise pick plain CSV.

Need a total rather than the rows themselves? Aggregate instead of exporting — a sum per month over 3 million rows is instant:

SELECT substr(order_date, 1, 7) AS month, SUM(amount) AS total
FROM data
GROUP BY month
ORDER BY month;

Is it really private?

Yes. The page is a static file; there is no server that could receive your data. You can check it yourself: open your browser's developer tools, go to the Network tab, and load a file — no request is made. Once the page has loaded you can even disconnect from the internet and keep working.

Other free CSV tools

Frequently asked questions