Regulex
A JavaScript regular-expression visualization project for diagrams of supported pattern syntax.
About Regulex
Regulex is a JavaScript project that parses regular expressions and draws them as diagrams. It parses a pattern into an abstract syntax tree and visualizes the supported pattern syntax. The project states that it runs in pure JavaScript without a backend. Its README also describes the graph being embedded on other sites through an HTML iframe element.
The parser reports detailed error messages, and in most cases it points to the exact position of a syntax error. Octal escapes are not supported. The project treats decimal escapes as back references, and it throws an error for invalid back references or for decimal escapes inside a character set. The README describes the project as under reconstruction. The project is open source under the MIT license and is listed as free.
Key features
- Parses JavaScript regular expressions into an abstract syntax tree
- Visualizes supported regular expression syntax as diagrams
- Written in pure JavaScript with no backend required
- Graph can be embedded on other sites through an HTML iframe
- Detailed syntax error messages, often pointing to the error position
- Installable with npm for Node.js; browser bundle can be built locally
Best for: Developers who work with JavaScript regular expressions and want a visual diagram of a pattern's structure.
Good for
- Runs in pure JavaScript with no backend required
- Open source under the MIT license
- Listed as free to use
Watch out for
- The README states that the project is under reconstruction
- Octal escapes are not supported; decimal escapes are treated as back references
- Invalid back references and decimal escapes inside character sets cause an error
Regulex at a glance
- Website
- github.com/CJex/regulex
- Category
- Development › Developer Tools
- Type
- Online tool
- Pricing
- Free
- Open source
- Yes
- Last checked
- Oct 9, 2026 · Online when checked
- Listed
- Oct 9, 2026
Guides for Developer Tools
Regulex alternatives
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Regulex FAQ
Can the regex diagram be embedded on another website?
The README says the graph can be embedded on other sites through an HTML iframe element.
How is Regulex installed for Node.js?
The README gives the install command npm install regulex. A browser bundle can be generated with a local build from the legacy branch.
How does Regulex handle octal escapes?
It does not support octal escapes. Decimal escapes are always treated as back references, and invalid back references cause an error.
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