Match all digits
Pattern: \d+
Text: Order 42 ships in 3 days
Flags: g
Matches: "42" and "3" — each run of one or more digits.No matches
About the Regex Tester playground
The Regex Tester lets you build and debug regular expressions against sample text in real time. Enter a pattern and some test input, and the tool highlights every match, shows captured groups, and updates instantly as you edit. This makes it easy to refine a pattern, understand why it does or doesn't match, and experiment with flags like global, case-insensitive, and multiline. It is ideal for crafting validation rules, search-and-replace expressions, and text-extraction patterns without trial-and-error in your code.
A regular expression is a compact, formal language for describing patterns in text. Built from literal characters and metacharacters, regexes let you match, search, and extract structured fragments such as emails, dates, or identifiers. Quantifiers control repetition, character classes define sets of allowed characters, anchors pin matches to positions, and groups capture sub-matches for reuse. Although the basic concepts are universal, exact syntax and supported features vary slightly between engines; this tester uses JavaScript's regular expression flavor.
HostedRegex Tester runtime
mainentry file
single fileworkspace
stdinprogram input
How it works
1
Write
The main file is the entry point for each run.
2
Give it input
Use the Input panel to pipe standard input to your program when it needs data.
3
Run
Run sends your code to a fresh hosted runtime and streams the result into the output panel.
4
Keep or share
Your draft stays in this browser, and Share creates a separate snapshot link.
External resources
- MDN Regular expressions— Format reference
Match email-like strings
Pattern: [\w.]+@[\w.]+\.\w+
Text: Contact us at [email protected] today
Matches: "[email protected]".Capture groups
Pattern: (\d{4})-(\d{2})-(\d{2})
Text: Date: 2026-06-14
Match: "2026-06-14"; group 1 = 2026, group 2 = 06, group 3 = 14.Anchored, case-insensitive
Pattern: ^hello
Text: Hello there
Flags: i
Matches: "Hello" — anchored to the start of the line, ignoring case.Optional letter (alternation via ?)
Pattern: \bcolou?r\b
Text: I prefer color over colour
Flags: g
Matches: "color" and "colour" — the "u" is optional.Lookbehind (price after $)
Pattern: (?<=\$)\d+
Text: price $50 and $100
Flags: g
Matches: "50" and "100" — a lookbehind requires a preceding "$" without including it.Hex colors with word boundary
Pattern: #[0-9a-fA-F]{6}\b
Text: use #ff0000 and #00FF00
Flags: g
Matches: "#ff0000" and "#00FF00" — exactly six hex digits.Backreference (doubled letters)
Pattern: (\w)\1
Text: balloon committee
Flags: g
Matches: "ll", "oo", "mm", "tt", "ee" — \1 repeats whatever group 1 captured.Match URLs
Pattern: https?://[^\s]+
Text: Go to http://a.com or https://b.org now
Flags: g
Matches: "http://a.com" and "https://b.org" — http or https, then non-space chars.Thousands-separated number
Pattern: \d{1,3}(,\d{3})+
Text: Sum 1,234,567 total
Flags: g
Matches: "1,234,567" — 1-3 leading digits then one or more comma-3-digit groups.How it works
The editor uses Monaco, the engine behind VS Code, with language-aware editing tools and familiar keyboard controls.
How it works
Enter a pattern, choose flags, and paste test input
Matches highlight live and update instantly as you edit
Captured groups are listed for each match
Options and features
Toggle flags like global, case-insensitive, and multiline
Inspect numbered and named capture groups
Try replacement expressions for search-and-replace
Privacy
Matching runs entirely in your browser
Your pattern and test text are never uploaded or stored on a server
Good to know
Uses JavaScript's regular expression flavor
Ideal for validation rules and text-extraction patterns without code trial-and-error
Every shortcut, searchable:
Editing
Undo
Ctrl+Z
Redo
Ctrl+⇧+Z
Select next occurrence
Ctrl+D
Delete line
Ctrl+⇧+K
Move line up / down
Alt+↑ / ↓
Copy line up / down
Alt+⇧+↑ / ↓
Toggle comment
Ctrl+/
Indent line
Ctrl+]
Outdent line
Ctrl+[
Navigation
Find
Ctrl+F
Find & replace
Ctrl+H
Go to line
Ctrl+G
Go to symbol
Ctrl+⇧+O
Selection
Select all
Ctrl+A
Select line
Ctrl+L
Select all occurrences
Ctrl+⇧+L
Shortcuts follow your OS — ⌘ becomes Ctrl on Windows and Linux.
It tests a regular expression against sample text, highlighting matches and showing captured groups live as you edit the pattern or input.
No. The pattern and your test text are processed entirely in your browser and are never sent to a server.
Yes. The Regex Tester is free to use with no account or limits.
Type your pattern in the pattern field and your sample text below it. Toggle flags like g, i, or m, and matches are highlighted instantly.
It uses JavaScript's regular expression engine. Most common syntax is portable, but some features differ from PCRE, Python, or other engines.
/
/gu
Up to 100,000 test characters; 10,000 pattern or replacement characters. Evaluation stops at 1,000 matches or 2 seconds.
Test String
Hello World
This is a Test string for Regex.
CamelCase is fun.
Flags
gGlobal — Find all matchesuUnicode — Unicode sequencesPattern
(Capturing group[A-Z]Any of: A-Z)End of group\wAny word character (letter, digit, _)+One or more (greedy)No matches found
Matches
No matches found
Explanation
Flags
gGlobal — Find all matchesuUnicode — Unicode sequencesPattern
(Capturing group[A-Z]Any of: A-Z)End of group\wAny word character (letter, digit, _)+One or more (greedy)