Search CSV Files with Regular Expressions

To search a CSV file with regex online, open your file in Large CSV Viewer and click the .* button in the search bar to enable regex mode. Type any valid regular expression to match rows across all columns simultaneously. Matching text is highlighted in yellow. You can also apply regex filters per column from the column filter panel.

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Use regex to search any CSV file online. Pattern match across all columns or a specific column — free, instant, no software needed.

Large CSV Viewer supports full regular expression search across your dataset. Toggle regex mode with one click and use any valid regex pattern to find exactly the rows you need — email addresses, phone numbers, date formats, or any custom pattern.

Key features

  • One-click regex mode toggle (the .* button in the search bar)
  • Regex applied across all columns simultaneously
  • Per-column regex filters also available
  • Matching text is highlighted in yellow in the results

How it works

  1. Enable regex mode. Click the .* button in the search bar to switch from plain-text to regular expression search mode.
  2. Enter your pattern. Type any valid regex pattern. For example, use ^\d{4}-\d{2}-\d{2}$ to find date-formatted values, or [a-z]+@[a-z]+\.[a-z]+ for email addresses.
  3. Review highlighted results. Matching text is highlighted in yellow across all visible rows. Apply the same pattern as a column filter for more targeted matching.

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Frequently asked questions

What regex syntax is supported?

Standard Python/RE2 regular expressions are supported, including character classes, quantifiers, groups, and lookaheads.

Can I use regex on a specific column only?

Yes. Click the column type icon to open the column filter panel, choose 'contains', and enter your regex pattern with regex mode enabled.

What happens if my regex is invalid?

The viewer will alert you that the regular expression is invalid and reset the search input. No rows will be filtered during the error state.

Can I use regex in find and replace?

Yes. Open Find & Replace (Ctrl+H) and enable the 'Regular Expression' checkbox to use a regex pattern as the find term.

Are regex searches case-sensitive?

By default, global regex search is case-insensitive. Use Find & Replace with the Match Case option for case-sensitive regex replacement.