Bulk Regex Matcher

About this tool

A regular expression tester is useful for one sample. Real cleanup and validation jobs usually start with a list: hundreds of IDs, email addresses, log lines, filenames, or pasted rows from a spreadsheet. This tool applies one regex to every line and reports the verdict for each line, so you can see both the matches and the failures without losing line numbers.

The report includes totals, the matched substring, capture groups, and optional byte offsets. Named capture groups such as (?<year>\d{4}) keep their names in text, JSON, and CSV output. Everything runs locally in your browser; the pasted data is not uploaded.

Worked example

Lines:

[email protected]
not-an-email
[email protected]

Pattern:

^[\w.+-]+@([\w-]+\.[\w.]+)$

With require whole-line match and capture groups on, the text report shows two matches and one failure:

Lines tested: 3
Matched: 2
Not matched: 1

line 1: MATCH    "[email protected]" | 1=example.com
line 2: NO MATCH "not-an-email"
line 3: MATCH    "[email protected]" | 1=test.org

Switch to CSV when you want one row per input line and one column per capture group, or JSON when another script will consume the result.

What you can control

• Pattern — Rust regex syntax. Use anchors (^...$) or turn on whole-line match for validation.
• Rows to show — all rows, only matching rows, or only non-matching rows. Totals always include every tested row.
• Output format — readable text, structured JSON, or CSV.
• Capture groups — include unnamed groups as 1, 2, and named groups by their names.
• Show match offsets — add start/end byte offsets to text and CSV. JSON always carries offsets.
• Trim each line and skip blank lines — enabled by default for pasted lists.
• Ignore case and dot matches newlines — common regex flags exposed as checkboxes.
• Max lines — default 1,000; maximum 20,000. Extra lines are skipped and the report says it was truncated.

Limits and edge cases

• This uses Rust's regex engine: no backreferences or look-around, but matching is linear-time and avoids catastrophic backtracking.
• Offsets are byte offsets in the tested line. For plain ASCII they match character positions; for emoji or other multi-byte characters they can differ.
• . does not match line breaks unless dot matches newlines is enabled. Because input is tested line by line, that flag is mostly useful for pasted records that contain embedded newlines after another tool has escaped or joined them.
• Blank lines are skipped by default. Turn off skip blank lines when blank rows are meaningful.
• The whole-line match option wraps your pattern as ^(?:pattern)$, so alternations such as yes|no are anchored as a group.

FAQ