Test Regex
Write and test regular expressions with live matching.
About Test Regex.
Test JavaScript Regular Expressions Live
Write a regex, paste test text, and CipherForces highlights every match in real-time. See capture groups, named groups, and all standard flags (g, i, m, s, u, y). Generate substitution previews with the replace function. Runs entirely in your browser.
Common Use Cases
- Build a validator: Test an email / URL / phone-number regex before shipping it.
- Log parsing: Craft a pattern to extract timestamps from application logs.
- Code migration: Test a find-and-replace regex before running it across a codebase.
- Data cleaning: Strip unwanted characters from a CSV column.
Key Features
- Live highlighting: Matches update as you type.
- Capture group breakdown: See each $1, $2, $3 match separately.
- Named group support:
(?<year>\\d{4})displays with its name. - Replace preview: See the output before running the substitution.
- Common-pattern library: One-click patterns for email, URL, phone, UUID, IP, date.
Privacy: Regex evaluation uses the browser's native engine. Nothing is transmitted.
Frequently asked questions.
Does my text get uploaded when I use this regex tester?
No. The regex tester runs entirely in your browser using JavaScript, so your pattern and test string never leave your device or reach a server. Nothing is uploaded and no signup is required. After the page loads it even works offline, which keeps sensitive text fully private.
How do I test a regular expression against sample text?
Type your pattern in the Pattern field, toggle flags like g, i, or m, then paste sample text into the Test String box. Matches highlight instantly as you type, and the Matches tab lists each result with its index. No button press is needed; results update live.
Can I see capture groups and test a find-and-replace?
Yes. The Groups tab shows each numbered and named capture group with its content, so you can confirm what your pattern captures. The Replace tab lets you enter a replacement using $1, $2, or $& for groups, then previews and copies the rewritten text instantly.
Is this regex tester accurate for Python, Go, or Java patterns?
It runs the JavaScript regex engine, so JavaScript patterns match exactly. For Python, Go, Java, Rust, and PHP, choose that flavor to see notes on syntax differences like named groups or unsupported lookarounds, but the actual matching still uses JavaScript rules.
How to use Test Regex.
Enter your input
Type or paste what you want to work with.
Choose settings
Adjust the options for what you need.
Get instant results
Your result updates right on the page.
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