Regex & Pattern Tools
Write and debug regex patterns with live match highlighting, get plain-English explanations of each token, generate patterns from examples, convert to code in 7 languages, and check for catastrophic backtracking vulnerabilities — all client-side. No uploads, no account, and no learning curve for translating a working pattern into your stack.
Most popular
- regexRegex Explainer● ready
Paste any regex pattern and see every token explained in human-readable English with beginner-friendly descriptions.
- regexRegex Visualizer● ready
Paste a regex and see it rendered as an interactive syntax diagram — groups, quantifiers, and alternations visualized as a flow chart.
- regexRegex Generator● ready
Paste positive examples (strings that should match) and optional negative examples (strings that should not), and get a generated regex pattern.
- regexRegex to Code● ready
Enter a regex pattern and choose a language — get the correctly escaped, ready-to-use code snippet for JavaScript, Python, PHP, Java, Go, Rust, or C#.
- regexReDoS Checker● ready
Paste a regex pattern and a test string to check for catastrophic backtracking — detects nested quantifiers, overlapping alternations, and other ReDoS risks.
Test & Explain
- regexRegex Explainer● ready
Paste any regex pattern and see every token explained in human-readable English with beginner-friendly descriptions.
- regexRegex Visualizer● ready
Paste a regex and see it rendered as an interactive syntax diagram — groups, quantifiers, and alternations visualized as a flow chart.
- regexRegex Patterns● ready
Browse or search a curated library of production-ready regex patterns: email validation, URL matching, IP addresses, phone numbers, credit cards, dates, hex colors, and 30+ more.
- regexRegex Flags● ready
Explore every JavaScript regex flag — what it does, when to use it, and a live test comparing the same pattern with and without each flag.
Build & Convert
- regexRegex Generator● ready
Paste positive examples (strings that should match) and optional negative examples (strings that should not), and get a generated regex pattern.
- regexRegex Escape● ready
Toggle: escape all special regex characters in your text for literal matching, or unescape a regex string back to its readable form.
- regexRegex to Code● ready
Enter a regex pattern and choose a language — get the correctly escaped, ready-to-use code snippet for JavaScript, Python, PHP, Java, Go, Rust, or C#.
Optimize & Check
- regexReDoS Checker● ready
Paste a regex pattern and a test string to check for catastrophic backtracking — detects nested quantifiers, overlapping alternations, and other ReDoS risks.
- regexRegex Optimizer● ready
Paste a regex and get back a simplified version with unnecessary groups removed, alternations merged, redundant quantifiers collapsed, and performance tips.
- regexRegex Grep● ready
Paste multi-line text and a regex pattern — see only the lines that match (grep mode), don't match (invert mode), or get match counts per line.
- regexRegex Diff● ready
Paste two regex patterns and see a token-by-token diff — identical parts in gray, additions in green, removals in red.
All tools
- regexRegex Explainer● ready
Paste any regex pattern and see every token explained in human-readable English with beginner-friendly descriptions.
- regexRegex Visualizer● ready
Paste a regex and see it rendered as an interactive syntax diagram — groups, quantifiers, and alternations visualized as a flow chart.
- regexRegex Generator● ready
Paste positive examples (strings that should match) and optional negative examples (strings that should not), and get a generated regex pattern.
- regexRegex Escape● ready
Toggle: escape all special regex characters in your text for literal matching, or unescape a regex string back to its readable form.
- regexRegex to Code● ready
Enter a regex pattern and choose a language — get the correctly escaped, ready-to-use code snippet for JavaScript, Python, PHP, Java, Go, Rust, or C#.
- regexRegex Patterns● ready
Browse or search a curated library of production-ready regex patterns: email validation, URL matching, IP addresses, phone numbers, credit cards, dates, hex colors, and 30+ more.
- regexReDoS Checker● ready
Paste a regex pattern and a test string to check for catastrophic backtracking — detects nested quantifiers, overlapping alternations, and other ReDoS risks.
- regexRegex Grep● ready
Paste multi-line text and a regex pattern — see only the lines that match (grep mode), don't match (invert mode), or get match counts per line.
- regexRegex Flags● ready
Explore every JavaScript regex flag — what it does, when to use it, and a live test comparing the same pattern with and without each flag.
- regexRegex Optimizer● ready
Paste a regex and get back a simplified version with unnecessary groups removed, alternations merged, redundant quantifiers collapsed, and performance tips.
- regexRegex Diff● ready
Paste two regex patterns and see a token-by-token diff — identical parts in gray, additions in green, removals in red.
About Regex & Pattern Tools
Regex tools for developers who write regular expressions daily. Test patterns with live matching and capture-group inspection, break down complex regexes into plain English, generate patterns from sample strings, convert to JavaScript/Python/PHP/Java, and check for ReDoS vulnerabilities before they reach production. Every tool runs in your browser — no uploads.
Related guides
Related categories
Frequently asked questions
What is regex?
A regular expression (regex) is a sequence of characters that defines a search pattern, used for string matching, validation, and text extraction across virtually every programming language.
What is ReDoS / catastrophic backtracking?
ReDoS (Regular Expression Denial of Service) happens when a regex pattern can cause exponential backtracking on certain inputs — freezing the browser or server. Our ReDoS checker detects patterns vulnerable to this.
Which regex flavors are supported?
These tools use JavaScript's regex engine (ECMAScript), which covers most common features. The Regex to Code converter helps you translate patterns to other language dialects with proper escaping.
Why does my regex match nothing when it works in another tool?
Most often the culprit is a flavor or flag difference: JavaScript treats some escapes differently than PCRE or Python, and flags like s (dotall), m (multiline), and g (global) change what a pattern matches. Test the pattern here with the same flags your code will use, then convert it to your language's dialect with the Regex to Code tool.