OpusDesk Hub What this tool does
Write and test regular expressions against sample text. View match counts, highlight matched text, extract capture groups, and understand match coordinates instantly in your browser.
How to use Regex Tester
- Enter Your Regular Expression Pattern. Type or paste your regex pattern into the pattern field, including any flags like global or case-insensitive. If you are used to a regex tester workflow, you will find the same instant feedback loop here — test your pattern against sample data without setting up a local environment.
- Provide a Test String. Paste one or more sample strings into the test input area that you want to match against your pattern. Like any good regex tester, the tool highlights every match in real time, showing you exactly which portions of your text the regular expression captures.
- Review Matches and Refine Your Pattern. Examine the highlighted matches and the detailed match info panel to understand capture groups and positions. Iterate on your pattern by editing it directly and watching the results update instantly — just like a dedicated regex tester, this rapid feedback loop helps you get your expression exactly right.
How this tool works
The component constructs a JavaScript RegExp from the pattern and flags, then applies it in a local worker to the sample text for matches and capture details.
- Engine: Native JavaScript RegExp
- Supported input: ECMAScript regular-expression source, JavaScript flags exposed by the UI, plain test text
- Output: match highlights, capture details
Worked example
Input: Pattern \b\d{4}\b with text 'Year 2026'
Output: One match: 2026
Limits, edge cases, and troubleshooting
Use short representative text while developing a pattern. Escape literal slashes only when your target syntax requires them.
- Matching runs in a local worker with a 500 ms processing limit and a maximum of 500 matches. Pattern input is limited to 10,000 characters and sample text to 100,000 characters.
- PCRE-, Python-, .NET-, and Java-specific syntax may differ or fail; The local worker stops a job after 500 ms; expensive patterns can be rejected.
When to use another workflow
Test in the actual target runtime when flavor-specific behavior, timeouts, Unicode modes, or production safety matters.
| Option | Best for | Trade-off |
|---|---|---|
| This browser tool | Quick, private, one-off work | Limited by browser memory and the documented feature set |
| Desktop or command-line tool | Batch jobs and repeatable automation | Requires installation and setup |
Supported inputs and limits
- ECMAScript regular-expression source
- JavaScript flags exposed by the UI
- plain test text
- Matching runs in a local worker with a 500 ms processing limit and a maximum of 500 matches. Pattern input is limited to 10,000 characters and sample text to 100,000 characters.
- PCRE-, Python-, .NET-, and Java-specific syntax may differ or fail; The local worker stops a job after 500 ms; expensive patterns can be rejected.
Frequently asked questions
Which regular-expression engine is used?
The browser’s JavaScript RegExp engine runs in a local worker. Other runtimes have different syntax and flags.
Can I perform replacements or test an expensive pattern?
This component displays matches and capture details, not replacement output. The worker is stopped after 500 ms; use short samples and test final behavior in the target runtime.
Is information sent to a server?
Tool inputs are processed in this browser. This product does not use analytics or send your input to an external API. Clicking an external website link still visits that website.