Regex Tester

Test and debug regular expressions, with AI assistance.

Regex Tester

Test and debug regular expressions in real-time.

Quick Patterns

Regular Expression

Flags

Test String

Match Preview

0 matches found

Regular expressions are a powerful tool for finding and extracting patterns in text. This tester lets you write, debug, and visualize regex patterns in real time, with color-coded match highlighting that makes it easy to see exactly what your pattern captures.

How to Use the Regex Tester

Enter your regular expression in the top field (without the surrounding slashes). Click the flag buttons to toggle modifiers such as g (global), i (case insensitive), and m (multiline). Type or paste your test string in the bottom field and matches will be highlighted instantly.

Use the Quick Patterns buttons to load common expressions for email, URL, phone number, and IPv4 validation. Click the sparkle icon to open the AI assistant, which can generate a regex pattern from a plain-English description.

Common Regex Patterns

Email: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,} — matches standard email addresses.

URL: https?://[^\s/$.?#].[^\s]* — matches HTTP and HTTPS URLs.

Phone (US): (?:$\d{3}$|\d{3})[-.\\s]?\d{3}[-.\\s]?\d{4} — matches formats like (555) 123-4567 or 555.123.4567.

IPv4: ((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?) — matches valid IP addresses from 0.0.0.0 to 255.255.255.255.

Date (YYYY-MM-DD): \d{4}-\d{2}-\d{2} — matches ISO-format date strings.

Frequently Asked Questions

What does the regex tester do?

It evaluates a regular expression pattern against a test string, highlighting all matches, showing capture groups, and indicating whether the pattern is valid.

How do I test a regex pattern?

Enter your regex pattern in the pattern field (without delimiters), type or paste a test string, and the tool highlights all matches in real time.

Can I use AI to generate a regex?

Yes. Describe what you want to match in plain English, and the AI assistant generates a regular expression pattern for you with an explanation.

What regex flavors are supported?

The tool supports JavaScript-style regex (ECMAScript), which covers most common use cases including lookaheads, capture groups, and character classes.

Is this regex tester free?

Yes, ToolDock's regex tester is completely free, requires no signup, and runs entirely in your browser.

Find and Replace

Find and replace text within a larger body of content.

Text Diff Checker

Compare two text files and highlight the differences.

String Escape / Unescape

Escape or unescape strings, including Unicode sequences.

How to Use the Regex Tester

Common Regex Patterns

Frequently Asked Questions

What does the regex tester do?

How do I test a regex pattern?

Can I use AI to generate a regex?

What regex flavors are supported?

Is this regex tester free?

Related Tools

How to Use the Regex Tester

Common Regex Patterns