Regex Tester

Developer Tools

Regex Tester

Test regular expression matches, groups, and replacements in the browser.

Input / output

Matches

2

Rendered

2

Capture groups

2

Input chars

15

Matches

abc def

Replacement preview

abc #123 def #456

Match table

#MatchStartEndLengthGroups
1234731
456121531

Capture group table

#GroupValue
1group 1123
2group 1456

Pattern explanation

  1. (\d+)Capturing group괄호 안 패턴을 캡처 그룹으로 저장합니다.
  2. \dDigit숫자 하나를 찾습니다.
  3. +One or more앞 토큰이 1회 이상 반복됩니다.

Quick reference

^

Start anchor

텍스트 또는 줄의 시작 위치에 고정합니다.

$

End anchor

텍스트 또는 줄의 끝 위치에 고정합니다.

\dused

Digit

숫자 하나를 찾습니다.

\w

Word

영문, 숫자, 밑줄 문자를 찾습니다.

\s

Whitespace

공백, 탭, 줄바꿈 같은 공백 문자를 찾습니다.

[]

Character class

대괄호 안 문자 집합 중 하나를 찾습니다.

()used

Capturing group

괄호 안 패턴을 캡처 그룹으로 저장합니다.

(?:)

Non-capturing group

캡처하지 않는 그룹을 만듭니다.

+used

One or more

앞 토큰이 1회 이상 반복됩니다.

*

Zero or more

앞 토큰이 0회 이상 반복됩니다.

{n,m}

Quantifier range

앞 토큰 반복 횟수의 범위를 지정합니다.

|

Alternation

왼쪽 또는 오른쪽 패턴 중 하나를 찾습니다.

Safety budget

Input limit
20,000 chars
Max matches
500
Worker timeout
300ms
Risk precheck
nested quantifier block

Tool usage summary

Use it before putting a regular expression into code or a document-processing workflow.

Processing
Text and patterns are processed with the browser regular expression engine without server storage.
Example
Use \d+ with abc 123 to see the 123 match and replacement preview.

Quick answer summary

Regex Tester checks pattern matches, capture groups, flags, and replacement output in the browser.

When to use it
Use it before putting a regular expression into code or a document-processing workflow.
Processing
Text and patterns are processed with the browser regular expression engine without server storage.
Example
Use \d+ with abc 123 to see the 123 match and replacement preview.
HelpOpen usage notes, examples, practical tips, and FAQ only when you need them.

What is this tool?

Regex Tester is a browser-first tool for test regular expression matches, groups, and replacements in the browser. It fits into the developer workflow and keeps the main task on one page.

How to use it

  1. Enter the input

    Paste or edit the value in the input area. Sample values are safe placeholders for testing the tool.

  2. Adjust options

    Choose the mode, format, unit, or count that matches the regex, regular expression, pattern test task.

  3. Review the result

    Run the tool, inspect the output, then copy or download it only when the result matches your expectation.

Examples

Regex Tester example

Input
Sample input
Output
Review the result in the browser.

Practical tips

  • For large inputs, process the smallest useful sample first to keep the browser responsive.
  • Ad slots are intentionally kept away from tool controls and result panes.

FAQ

What input should I use with Regex Tester?

Use values that match the regex, regular expression task, then adjust the visible options before running the tool.

Can I copy the Regex Tester result?

Yes. Review the output first, then copy or download it when the result matches your expectation.

Can I use Regex Tester on mobile?

Yes. The input, options, action, and result areas are designed to stack cleanly on small screens.

Will ads interrupt Regex Tester?

No. Ad slots stay outside the input, output, and primary action areas so the tool remains usable and policy-safe.

Can Regex Tester show capture groups and replacement output?

Yes. It previews matches, capture groups, flags, and replacement output before you use a pattern in code.

Are regex test inputs stored on a server?

No. Text and patterns are processed by the browser regular expression engine without server storage.

How can I spot a slow regular expression?

Try longer sample input and simplify nested groups or repeated quantifiers before moving the pattern into production code.

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