Debuggex

Debuggex is a web-based visual regex tester for JavaScript, Python, and PCRE. It provides visual and text views for examining expressions, along with a step-through debugger and pattern explanations. Users can add unit tests to check matches and subgroups as a regex changes, or browse a repository of pre-built expressions that includes tests. The service can generate code snippets, save patterns, and create links that reopen an expression; users can also embed expressions 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. The free tier excludes snippets that use expressions from the library. 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. Debuggex's privacy policy says saved or shared expressions can be viewed by anyone with the link, and previous versions are stored after updates. It is available on the web.

Debuggex pairs regex inspection with testing, sharing, and a repository of pre-built expressions. Consider the free tier's limits and link visibility when deciding whether it fits your workflow.

Debuggex suits developers and other users who need to inspect or test regular expressions in JavaScript, Python, or PCRE. Its unit tests and shared links may also help people who maintain or discuss patterns with others.

Debuggex is a browser-based visual regex tester for JavaScript, Python, and PCRE. It is best suited to developers who want to inspect patterns and check them against reusable tests. The combined debugger and tested-expression repository are useful strengths, but saved-work limits and link visibility matter.

Overview

Debuggex pairs visual and text views with a step-through debugger and plain-English explanations on Basic and Pro. Unit tests let users check matches and subgroups as a pattern changes, which is more useful for iterative work than relying on a single sample string.

Its repository includes pre-built expressions with unit tests. Basic users can compose expressions from repository entries, while Pro users can compose from any expressions. Sharing links reopen an expression, and an embed option is available for StackOverflow answers. Saved or shared expressions can be viewed by anyone with the link, and previous versions remain stored after updates, so links are convenient for collaboration but unsuitable for sensitive patterns.

Key features

• Visual and text inspection: The two modes and step-through debugger help users examine a regex’s structure and behavior, rather than treating it as an opaque string.
• Unit tests: Tests check matches and subgroups as expressions change. The free tier saves only two tests per regex, so users with larger test sets will need Basic or Pro.
• Repository and composition: The tested library can speed up common pattern work. Basic composition is limited to repository expressions; Pro extends it to any expressions.
• Code generation: Debuggex generates code snippets from regexes, but the free tier excludes snippets that use library expressions.
• Privacy and account data: The privacy policy says the service does not sell collected user data without express permission and stores account email, not passwords. It also lists Google Analytics and Mozilla Persona.

Pricing

All listed monthly prices are billed monthly. Free is free and includes the visualizer, debugger, and JavaScript engine; Python and PCRE engines are free while in beta. It saves two unit tests per regex and ten public expressions. This is a sensible starting point for occasional testing, but its saved-work caps and library-snippet exclusion narrow its usefulness for sustained work.

Basic costs $5 a month. It raises the test allowance to five per regex, permits unlimited public expressions and 20 private expressions, and adds plain-English explanations, regex replacement, a unit-tested repository, and repository-based composition. It suits users who want the library and more room to save work, but the private-expression cap and test limit remain.

Pro costs $15 a month and removes the per-regex test cap and private-expression limit. It also adds composition using any expressions, performance debugging, and unit-test coverage. This is the better fit for heavier testing and private saved work; users who do not need those expanded limits may find Basic sufficient.

Enterprise has custom pricing. Its options include denial-of-service prevention, flexible user counts, private-server deployment, an OEM license, and on-site training, making it the plan for organizations with deployment or licensing needs rather than individual users.

Platforms

Debuggex runs on the web. Its supported regex flavors are JavaScript, Python, and PCRE; Python and PCRE are marked free while in beta.

Who it's for

Choose Debuggex if you work in a browser and want to understand a regex, verify match and subgroup behavior, or reuse tested expressions. It is less suitable for confidential patterns shared by link, or for workflows that need generous saved-test and private-expression limits without paying for Pro.

Pros and cons

Pros

• Tests alongside visual debugging: Inspecting structure and checking behavior in the same tool supports more careful iteration.
• Tested expression repository: Pre-built patterns and composition can reduce repeated work, especially on Basic and Pro.
• Clear upgrade path: Basic adds private saves and a larger test allowance; Pro removes key saved-work limits and adds performance debugging and coverage.

Cons

• Restrictive free saves: Two tests per regex and ten public expressions can constrain regular use.
• Link visibility: Anyone with a saved or shared expression’s link can view it, and prior versions are retained.
• Some free-tier exclusions: Library-based snippets are excluded, and Python and PCRE engines are free only while in beta.

Alternatives

Browse regular expression testers for more options. Choose AppTools Regex Tester if you want a free core utility suite across Android, iOS, Linux, macOS, web, and Windows without sign-up or subscription. RegexRegex is a free web tester if JavaScript checks in the browser are enough; Python, PHP, Java, .NET, and Perl checks require an explicit online run.

regex101 is another freemium option, with a free plan and a trial. RegexCraft is a freemium alternative for Linux, macOS, and Windows. RegexPilot offers a free JavaScript and TypeScript plan and a €19 one-time license for all 21 flavors. RegExr is a free web tool for learning, building, and testing regexes. Retest is a free Linux option. The Regex Coach is a free alternative for Linux and Windows.

Verdict

Debuggex is a strong choice for browser-based regex work when visual inspection, unit tests, and a reusable expression library matter together. Start with Free for light use, move to Basic for library features and more saved work, or choose Pro for unrestricted saved tests and private expressions. Look elsewhere if you need patterns kept private from anyone holding a link or want broad saved-work capacity without a paid plan.