Regex Tester
Test regular expressions live
Free forever — no sign-up, nothing uploaded. Files never leave your device.
Regex Tester
Test regular expressions live
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About this tool
Write a regex, see matches highlighted in your text, and test flags and capture groups.
The Regex Tester is a powerful live正则表达式 testing environment that highlights matches in real time as you type your pattern and input string. It eliminates the guesswork from regular expressions by visually showing exactly which substrings match your regex, making it indispensable for validating email patterns, scraping rules, input sanitization logic, and log parsing workflows.
Supporting full JavaScript regex syntax including lookahead, lookbehind, named capture groups, and all standard flags (g, i, m, s, u, d), this tool displays match results, group captures, and index positions instantly. The live highlighting overlay on the input text gives you immediate visual feedback — no need to click a "test" button or wait for processing.
Every character of your input stays in your browser. There's no server processing, no account creation, and no waiting — just a fast, precise regex development environment for developers, data engineers, and security professionals.
Key features
Everything you get with Regex Tester — no premium upsell.
Live match highlighting as you type the pattern
Full JavaScript regex engine with all flags (g, i, m, s, u, d)
Named and numbered capture group results with index positions
Supports lookahead, lookbehind, and advanced pattern constructs
Client-side only — regex patterns and test strings never leave your browser
Quick-reference panel for common regex tokens and shortcuts
How to use Regex Tester
Follow the steps below to use the tool.
- 1
Enter Your Regex Pattern
Type your regular expression into the pattern field. Slashes are added automatically.
- 2
Set Flags
Toggle flags like global (g), case-insensitive (i), multiline (m), and dotAll (s) using the provided checkboxes.
- 3
Provide Test Input
Paste or type your test string into the input area. Matches are highlighted live as you type.
- 4
Review Match Details
Inspect the match results panel for full match text, capture groups, and character index positions.
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Launch Regex TesterFrequently asked questions
Quick answers before you launch the tool.
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