Debuggex
Debuggex is an online visual regular-expression tester for JavaScript, Python, and PCRE.
What Debuggex is
Debuggex is an online visual regular-expression tester for JavaScript, Python, and PCRE. It provides visual and text modes for examining expressions, plus a step-through debugger and pattern explanations. Users can add unit tests to check matches and subgroups as a regex changes, and browse a repository of pre-built expressions with unit tests. The service can generate code snippets, save patterns, and create links that reopen an expression; expressions can also be embedded in StackOverflow answers. The Free plan costs nothing and includes two saved unit tests per regex and ten public expressions. Basic costs $5 a month, and Pro costs $15 a month. Enterprise has no listed price and includes options such as private server deployment, denial-of-service prevention, flexible user counts, an OEM license, and on-site training. The free tier excludes snippets that use expressions from the library. Debuggex's privacy policy says saved or shared expressions can be viewed by anyone with the link.
Good
- Supports JavaScript, Python, and PCRE.
- Includes visual and text expression views.
- Unit tests can check matches and subgroups.
- Shareable links reopen expressions.
Watch out
- Free plan limits saved tests and public expressions.
- Free tier excludes snippets using library expressions.
- Shared or saved expressions are viewable by anyone with the link.
Who it suits
Debuggex suits people who need to inspect and test regular expressions for JavaScript, Python, or PCRE. Its unit tests and expression repository may be useful for users building or maintaining patterns.
Verdict
Debuggex combines regex inspection, testing, and sharing in a web tool. Review the plan limits and link visibility if you need private expressions or library-based snippets.
Plans and prices
From Debuggex's own pricing page, checked 15 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Free | Free | Regex visualizer · Regex debugger · JavaScript engine · Python engine (beta) · PCRE engine (beta) · code snippets · 2 unit tests per regex · 10 public expressions · per month |
| Basic | $5 a month | 5 unit tests per regex · unlimited public expressions · 20 private expressions · plain-English explanation · regex replace · unit-tested repository · repository composability · per month |
| Pro | $15 a month | Unlimited unit tests · unlimited private expressions · composability using any expressions · performance debugging · unit-test coverage · per month |
| Enterprise | Priced on request | Denial-of-service prevention · flexible user counts · optional private-server deployment · optional OEM licence · optional on-site training |
The facts
Each one read from Debuggex's own pages, with the date it was checked.
What it does
- Built-in testing
- Users can add unit tests and check whether matches and subgroups behave as expected when a regex changes.checked 30 Sep 2026
- Cheatsheet
- A built-in flavor-specific regex quick reference covers operators such as groups, assertions, quantifiers, anchors and escapes.checked 15 Oct 2026
- Code generation
- Repository expressions can be compiled into a language-specific code snippet from the interface.checked 15 Oct 2026
- Code snippets
- The product can generate a code snippet from a regex, while the free tier excludes snippets using expressions from the library.checked 30 Sep 2026
- Early commercial traction
- The founder later wrote that Debuggex sold one $4,000 licence in its first six months and generated about $25 per month in subscriptions.checked 15 Oct 2026
- Early outage
- In a 26 April 2013 founder post, Debuggex reported two brief outages affecting fewer than ten users at the time.checked 15 Oct 2026
- Enterprise deployment
- The Enterprise plan offers optional private-server deployment and an optional OEM licence.checked 15 Oct 2026
- Expression library
- The product includes a searchable library of saved expressions and can generate snippets from expressions.checked 15 Oct 2026
- Expression visibility
- The privacy policy says saved or shared expressions are viewable by anyone with the link and that previous versions are stored after updates.checked 30 Sep 2026
- Independent listing
- AlternativeTo describes Debuggex as a freemium, proprietary website in the development category and lists more than 25 alternatives.checked 15 Oct 2026
- Integrations
- The site offers an embed option for StackOverflow and lists Google Analytics and Mozilla Persona in its privacy policy.checked 30 Sep 2026
- Launch timing
- The founder says he launched the regex tester about two months before his 26 April 2013 article, placing the initial launch in early 2013.checked 15 Oct 2026
- Licence
- Debuggex states that its own software is not open source.checked 15 Oct 2026
- Limit: commercial perception
- A Reddit discussion included a complaint that Debuggex felt commercial and lacked a quick reference, although another commenter linked to its quick reference.checked 15 Oct 2026
- Limit: interface age
- Scraping.Pro characterized the interface and feature set as dated compared with newer regex testers.checked 15 Oct 2026
- Limit: named groups and flags
- Webscraping.pro reported limited named-group functionality and support for only a limited set of regex flags.checked 15 Oct 2026
- Limit: paste workflow
- A Stack Overflow commenter wished Debuggex allowed pasting text directly into the tool.checked 15 Oct 2026
- Limit: workflow breadth
- Scraping.Pro’s review says Debuggex is thinner than newer tools for substitution previews, broad explanations and code generation, and lacks substitution testing.checked 15 Oct 2026
- Live matching
- Matches and non-matches update in real time while the expression and test text are edited.checked 15 Oct 2026
- Praise: community users
- Reddit commenters repeatedly described the tool as useful for learning, immediate visual feedback, explaining regexes and generating code.checked 15 Oct 2026
- Praise: learning
- A C.W.K. regex lesson recommends Debuggex when learners need to understand a complex pattern through its railroad diagram.checked 15 Oct 2026
- Praise: unique diagrams
- Scraping.Pro’s 2026 review says Debuggex remains unusually strong for showing a tangled pattern’s structure as a railroad diagram.checked 15 Oct 2026
- Praise: visualisation
- Webscraping.pro praised the central visual diagram, live highlighting and slider-based step-through as useful for understanding complex matches.checked 15 Oct 2026
The company
- Company identity
- Founder Serge Toarca identifies the incorporated business as Debuggex Inc. and calls Debuggex his first product.checked 15 Oct 2026
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