Large CSV file viewer: open huge CSV files online, free

How to view a large CSV file

1. 1Open your CSV file. Drop the file onto the viewer at the top of this page, or click “Choose a file”. The separator, decimal commas, the text encoding and the header row are detected for you, so a semicolon-separated export from a European Excel opens just as well.
2. 2Scroll through the rows. The data table opens first. Scroll through every row, however many there are; each column header shows the column’s type (number, date and time, duration, text or category) and its unit, where the file has one. The number of rows and columns is shown above the table.
3. 3Sort and filter the rows. Point at a column header and click its arrows to sort by that column (Shift-click adds a second one). For more, right-click the header, or click the ▾ at its right: Sort ascending, Sort descending and “Filter…”, which keeps only the rows you need, such as temperatures above 30 or one city. On a phone or tablet, tap the header. The count above the table shows how many rows are left.
4. 4Check the columns and chart them. Search the column list by name, and open the statistics panel for the count, missing values, minimum, maximum, mean and standard deviation of any column. Click a column header to plot it, and switch to “Split” in the toolbar to see the chart above the table.

No file to hand? Click Try a 1-million-row CSV in the viewer: it opens 1,000,000 hourly readings of made-up UK weather, made on your device. Or download one of the large sample CSV files to try, up to 100,000 rows.

What you can do with it

Scroll millions of rows

The table shows every row of the file, not a preview of the first thousand. It only draws the rows on screen, so scrolling stays smooth at 10 million rows, and the scroll bar takes you anywhere in the file.

See what each column holds

Each column is recognised as numbers, dates and times, durations, text or categories. Units come from a units row under the header, or from the values themselves, such as % or £. Numbers are right-aligned, and a decimal comma is read as a decimal.

Statistics in a click

The statistics panel gives the count, missing values, minimum, maximum, mean, median, quartiles and standard deviation of a number column, or the distinct and most frequent values of a text column, calculated from every row.

Find a column fast

Exports with hundreds of columns are easy to find your way around: the column list has a search box, groups columns with a shared prefix and can be made wider.

Chart any column

Plot a column against time or another column, add more charts side by side and zoom into a moment. The table jumps to the first row in view, and hovering a chart highlights the row under the cursor. With stacked lanes you can compare CSV signals on a shared time axis, each with its own Y axis.

Several files at once

Choose or drop more than one file to open them together: each gets its own tab in the table, and their columns can be plotted and compared side by side.

How big a CSV can it open?

There is no fixed row limit and no file-size cap: the practical limit is your device’s memory. In our tests in Chrome on a recent laptop:

• a 143 MB CSV with 2,000,000 rows and 9 columns opened in about 1 second;
• a 423 MB CSV with 10,000,000 rows and 5 columns opened and drew its first chart in about 3 seconds;
• a 1.4 GB export with 28 million rows opened, with its 1,900 signals split into channels.

Measured in Chrome on a recent laptop (Apple M4): a 423 MB CSV with 10,000,000 rows and 5 columns, from choosing the file to the first chart. Slower devices take longer.

The table draws only the rows on screen, so scrolling stays smooth however long the file is. Phones and older computers have less memory: a file of several hundred megabytes is best opened on a laptop or desktop.

How we time these files, cold and warm, on which machine and browser, and where the limits are: how we measure speed.