⌘ K
match count · frequency · upload

Count matches and see the most-frequent ones

Sweep a regex across pasted text or an uploaded .txt file. Get totals, uniques, longest, and a frequency table. Runs locally.

Regex Match Counter
Total
12
matches
Unique
9
distinct
Avg length
3.75
max 5
Top
×3
"the"
Flags
input · pattern + sample
//g
output · frequency table
count
match
3
"the"
2
"fox"
1
"quick"
1
"brown"
1
"jumps"
1
"over"
1
"lazy"
1
"dog"
1
"runs"
Quick Start

How to count regex matches

Run any regex over text or a .txt upload and read total, unique, longest, and most-frequent match counts.

  1. 01

    Paste pattern + flags

    Pick a regex and your flag set — g is forced on internally so all matches are counted.

    Patterns compile through the JavaScript RegExp constructor, so syntax errors surface immediately and engine quirks like Unicode property escapes (\p{L}) work when the u flag is on.

    patternECMAScriptliterallive
    input · literalpattern · regex
    \b\w+\b
    loaded · ECMAScriptPCRE · ready
  2. 02

    Add sample text

    Paste text or upload a .txt file. The counter sweeps the whole input.

    Each flag character mirrors the ECMAScript literal: g enables iteration, i folds case, m anchors per line, s lets . match newlines, u unlocks proper Unicode, y is sticky, and d emits indices.

    flagsoptionsg · i · mlive
    sample · optionstext · flags
    upload .txt
    flags applied · liveECMA · live
  3. 03

    Read the stats

    Total, unique, average length, longest, and the most-frequent match come back as cards.

    Watch for catastrophic backtracking on nested quantifiers — a common ReDoS source. The tool caps match counts to keep the page responsive on pathological patterns.

    matchgroupshighlightReDoS-safe
    stats · outputsummary · matches
    11 / 7 / 3.7
    matches · livegroups · live
  4. 04

    Copy or export

    Grab the output as JSON, CSV, or plain text — ready for your editor or pipeline.

    Copy writes via navigator.clipboard.writeText; downloads use a Blob and object URL, so nothing transits the network and the output is byte-identical to what you see on screen.

    copyexportclipboardblob
    export · exportedready · saved
    Copied
    ready to shipsuccess
Pro tips

Regex patterns that don't melt down

Use named groups

(?<year>\d{4}) reads better than $1 and survives reordering. Supported in ECMAScript 2018+.

Anchor strictly

Use ^/$ with the m flag when matching whole lines. Without anchors, partial matches sneak through.

Avoid catastrophic backtracking

Nested quantifiers like (a+)+ can explode. Run patterns through ReDoS Detector first.

Escape every literal

Backslash any meta character you want literally: \.\$\^\*\+\?\(\)\[\]\{\}\|\\.

Test edge cases

Empty string, single character, unicode, the maximum length you expect — write fixtures for each.

Patterns aren&rsquo;t parsers

Don’t parse HTML, JSON, or balanced parens with regex. Use a proper parser when the grammar is recursive.

Related toolsRegex TesterRegex Find AllRegex Performance BenchmarkRegex DebuggerRegex Extract GroupsRegex Keep Matches
Use Cases

When match counting helps

Get the shape of a corpus before transforming it.

Profile a corpus

Word frequency, tag counts, hashtag use. Compiles through the JavaScript RegExp constructor — engine quirks (Unicode property escapes, sticky matching, named groups) work when their flags are on. Error messages cite the exact position of any syntax issue.

ReDoS-safe

Audit a log

How many ERROR lines? Most common path? Pairs with the ReDoS detector to catch catastrophic backtracking before you deploy. A pattern that handles 1k-character input fine can become a denial-of-service vector on attacker-controlled 1M-character input.

ECMA-compliant

Tune a pattern

Compare candidate patterns by match count. Output exports as JavaScript, Python re, Java util.regex, .NET System.Text.RegularExpressions, PCRE, and POSIX — language quirks are highlighted on conversion so you don't ship a JS-only pattern to a Go service.

spec-grade

Sanity-check tests

Confirm fixtures contain expected hits. Capture groups (named or numbered) round-trip cleanly into replacement strings, JSON output, or CSV extraction without re-typing. Backreferences ($1, ${name}) preserve semantics across languages.

cross-engine

Build dictionaries

Sort by frequency to pick top tokens. Test against edge cases — empty input, single character, max length, multibyte boundaries — to catch off-by-one and zero-length match bugs before they reach production.

test-ready

Share findings

Copy the table into a ticket or PR. All matching runs client-side so secret patterns never leave the browser. Useful when the pattern itself is sensitive (PII regexes, internal data formats, security filters).

production-ready
FAQ

Frequently asked questions

Yes — the helper caps at 100,000 to keep pathological patterns from freezing the page.
No. Uploaded files are read in-browser only — nothing leaves your machine.
Counting only makes sense across the whole input. Without g most engines stop at the first match.
By exact match text. Two matches that differ in case are considered distinct unless i is on.
No. The tool runs entirely in your browser — your pattern and sample text never leave the page.
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