Regex Tester Pro
Test and debug regular expressions right in your browser. Real-time highlighting, match group visualization, and code export to 8 programming languages – all without leaving Chrome.
Regex Tester Pro is a free, open source tool that lives in your browser toolbar. No need to visit external regex websites or switch context when you are deep in a coding session.
Install Free from Chrome Web Store View Source on GitHub
Why Regex Tester Pro?
Regular expressions are powerful but notoriously tricky to get right. Most developers test them by switching to a web-based regex tool, then copying the pattern back into their code. That workflow breaks your focus.
Regex Tester Pro puts a full-featured regex testing environment in your browser toolbar. Click the icon, type your pattern, paste your test string, and see matches highlighted in real time. When you are done, export the working regex directly as code in your language of choice.
Key Features
- Real-time match highlighting – See matches update instantly as you type your pattern or test string
- Match group visualization – View captured groups, named groups, and backreferences clearly
- Code export to 8 languages – Generate ready-to-use regex code for JavaScript, Python, Java, C#, PHP, Ruby, Go, and Rust
- Flag controls – Toggle global, case-insensitive, multiline, dotAll, and Unicode flags
- Match counter – See the total number of matches at a glance
- Pattern history – Your recent patterns are saved for quick access
- Common patterns library – Browse and insert frequently used patterns (emails, URLs, dates, and more)
- Performance analysis – Get warnings about potentially slow or catastrophic backtracking patterns
- Works completely offline – No server connection needed, ever
- Pattern explainer – Get a plain-language breakdown of what your regex does
Built for Your Development Workflow
Regex Tester Pro is designed to minimize context switching:
- Write a regex in your editor – Click the extension icon to test it without leaving Chrome
- Debug a failing pattern – Paste your input and pattern to see exactly what matches (and what does not)
- Learn regex – Use the pattern explainer to understand complex expressions
- Export to code – Generate production-ready regex code for your target language
- Common patterns – Quick-insert patterns for common validation tasks instead of writing from scratch
Privacy and Security
Regex Tester Pro runs entirely in your browser:
- No data is sent to any server
- No analytics or tracking
- No account required
- Works fully offline
- Full source code on GitHub
Your patterns and test strings stay on your machine. Always.
How It Works
- Install the extension from the Chrome Web Store
- Click the icon in your browser toolbar to open the tester
- Enter your regex pattern in the pattern field
- Paste your test string and see matches highlighted instantly
- Adjust flags (global, case-insensitive, multiline, etc.)
- Export working patterns as code in your preferred language
Frequently Asked Questions
Does Regex Tester Pro work offline?
Yes. The entire extension runs locally in your browser. There are no server calls, no internet requirement. You can test regex patterns on an airplane.
Which regex flavor does it use?
Regex Tester Pro uses JavaScript’s built-in RegExp engine, which supports standard regex syntax including lookahead, lookbehind, named groups, and Unicode properties.
Can I export regex code for my programming language?
Yes. The code export feature generates ready-to-use regex code for JavaScript, Python, Java, C#, PHP, Ruby, Go, and Rust. The exported code includes the pattern, flags, and example usage.
What is the performance analysis feature?
Regex Tester Pro detects patterns that may cause catastrophic backtracking – a common issue where certain regex patterns can take exponentially long to process on certain inputs. You get a warning before shipping a problematic pattern.
How does the pattern explainer work?
The explainer breaks down your regex into individual components and describes what each part does in plain English. This is useful for understanding complex patterns written by others or learning regex syntax.
More Free Chrome Extensions by Zovo
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- JSON Formatter Pro – Format and validate JSON in your browser
- Cookie Manager – View, edit, and export browser cookies
- Clipboard History Pro – Save and search your clipboard history
Regex Tester Pro is built and maintained by Zovo. Open source. No tracking. Just regex.