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RegexPlanet
What it is
RegexPlanet is a free web service for testing regular expressions during development. It offers separate tester pages for many regex flavors, including Java, Python, Bun, Go, Deno, Erlang, Haskell, MySQL, .NET, Node.js, Perl, PHP, PostgreSQL, Ruby, Rust, Swift, Tcl, XRegExp, and the browser. The Java page accepts a pattern, replacement text, and multiple input strings, with a control for adding more inputs. Controls include case-insensitive matching, multiline mode, and Unicode-aware case folding. A share-code field supports exchanging regexes, while Regex Zone is suggested for sharing expressions and finding common patterns. A status page reports each engine and says engines run in separate instances. The maker warns that malformed expressions can run indefinitely and that some engines or hosts may face denial-of-service attacks. The privacy policy says IP addresses, user agents, other browser data, and form entries are collected. Raw logs are stored by Google CloudRun. The service is provided as-is and as-available, with a contact form for questions.
For and against
For
- Free public web service
- Many regex engine flavors
- Java tester supports multiple inputs
- Engine options include Unicode-aware folding
- Share-code field for regexes
Against
- Malformed patterns may run indefinitely
- Some hosts may face denial-of-service attacks
- Form entries and browser data are collected
- Service availability is not guaranteed
The verdict
RegexPlanet provides broad, browser-based regex testing with detailed Java controls and many engine choices. Review its security and data-handling warnings before entering sensitive material.
Who it suits
It suits developers who need browser-based regex testing across many engines. It is also useful for people sharing patterns through codes or Regex Zone.
Plans and prices
Free public service
Website for testing regular expressions · provided free to the public
Read 8 Oct 2026 · regexplanet.com
On the record
- Data storage
- The privacy policy says the maker does not store data locally and that raw log files are stored by its cloud provider, currently Google CloudRun.regexplanet.com · read 8 Oct 2026
- Engine options
- The Java tester exposes engine options such as case-insensitive matching, multiline mode, and Unicode-aware case folding.regexplanet.com · read 8 Oct 2026
- Engine status
- A status page reports the status of each engine and says each engine runs in a separate instance.regexplanet.com · read 8 Oct 2026
- Open source repository
- The maker's GitHub repository describes a next-generation version and lists the GNU Affero General Public License v3.0 or later.github.com · read 8 Oct 2026
- Privacy data
- The privacy policy says the site collects IP addresses, user agents, other browser-sent data, and anything entered into forms.regexplanet.com · read 8 Oct 2026
- Purpose
- RegexPlanet is a website for testing regular expressions during development.regexplanet.com · read 8 Oct 2026
- Regex community
- The site directs users to Regex Zone to share regular expressions and find common patterns.regexplanet.com · read 8 Oct 2026
- Regex engines
- The site provides regex test pages for engines including Java, Python, Bun, and Go.regexplanet.com · read 8 Oct 2026
- Security limitation
- The maker warns that badly formed regular expressions can run indefinitely and that some engines or hosts may be susceptible to denial-of-service attacks.regexplanet.com · read 8 Oct 2026
- Share codes
- The home page describes share codes as a way to share regexes and provides a field for entering one.regexplanet.com · read 8 Oct 2026
- Support
- The site provides a contact form for questions and inquiries.regexplanet.com · read 8 Oct 2026
- Terms and availability
- The terms describe the service as provided as-is and as-available, without a warranty that it will be available, uninterrupted, secure, or error-free.regexplanet.com · read 8 Oct 2026
- Test inputs
- The Java tester has fields for a regular expression, replacement, and multiple input strings, with a control to add more inputs.regexplanet.com · read 8 Oct 2026
