Best Online Regex Testers for Web Scraping

Before shipping a regular expression into production code, it's worth proving it against real sample text — and ideally against the exact regex engine you'll be targeting, because flavors differ in subtle, frustrating ways (lookbehind, named groups, Unicode handling, and so on). An online tester lets you do that in seconds, usually with live match highlighting, an explanation of what each token does, and a quick syntax reference at your elbow.

This guide rounds up the testers that are still worth using, flags the ones that have gone stale or shut down, and adds several modern tools that didn't exist when lists like this were first written. A comparison table sits at the end.

Recommended general-purpose testers

regex101

Site: https://regex101.com

The de facto standard. regex101 lets you build, test, and debug patterns with real-time match highlighting, and — its standout feature — a running, plain-English explanation of your expression as you type. It supports several engines side by side: PCRE2, PHP, Python (re), JavaScript, Java, .NET (C#), Go (RE2), and Rust. A built-in quick reference, a step-by-step regex debugger, a code generator for the major languages, and shareable permalinks round it out. It's free, with an optional paid tier that removes ads and adds quotas. If you only learn one tool, make it this one.

RegExr

Site: https://regexr.com · Source: https://github.com/gskinner/regexr

RegExr is the modern successor to Grant Skinner's original Flash-based tester (see the legacy note below). Rewritten in HTML/JS, it's now an open-source project (GPL v3) and one of the most pleasant tools to use. It supports JavaScript and PHP/PCRE flavors, real-time highlighting, hover-for-detail on any token, a built-in cheat sheet and reference, save-and-share permalinks, a "Tests" panel for validating a pattern against multiple cases, and a searchable library of community patterns. Dark mode included.

RegexPlanet

Site: https://www.regexplanet.com

RegexPlanet is the tool to reach for when you need to match against an unusual engine. It now covers a remarkably broad set: JavaScript, Java, .NET, Python, Perl, PHP, Ruby, Go, Rust, Swift, Tcl, PostgreSQL, Node.js, Bun, Deno, and XRegExp. You can test several input strings at once and see how each language's match/replace functions behave. It doesn't generate copy-paste code, but for cross-engine verification it's hard to beat.

Debuggex

Site: https://www.debuggex.com

Debuggex visualizes your pattern as a railroad diagram, which makes the structure of a complex expression far easier to reason about. It supports JavaScript, Python, and PCRE, with live match highlighting and shareable permalinks. Worth keeping in your kit specifically for untangling patterns someone else wrote.

Rubular

Site: https://rubular.com

Rubular is a clean, fast, single-purpose editor for the Ruby regex engine (it also reflects Ruby version differences). No replace or split functions — it's deliberately minimal — but for Ruby developers it remains the go-to.

Language-specific testers

Pythex (Python)

Site: https://pythex.org

Pythex is a tiny, fast editor for Python's re module that runs entirely in your browser. Live highlighting, a match/group breakdown, and a handy cheat sheet. The closest thing to "what Python will actually do" without opening a REPL.

PyRegex (Python)

Site: http://www.pyregex.com

PyRegex is another online checker focused on Python's regex subset — a simple alternative to Pythex.

Regex Storm (.NET)

Site: https://regexstorm.net/tester

Regex Storm runs the actual .NET Regex class, with highlighting and detailed match/group output. With the original Silverlight-based .NET testers gone, this is the most reliable browser option for C#/VB.NET patterns.

PHP Live Regex

Site: https://www.phpliveregex.com

A PHP-specific tester with live evaluation and code generation for each of PHP's regex functions (preg_match, preg_match_all, preg_replace, preg_split, and so on).

RegexLib

Site: https://www.regexlib.com · Tester: https://www.regexlib.com/RETester.aspx

RegexLib is best known for its large, searchable community database of regular expressions — handy when you want a battle-tested pattern for emails, URLs, dates, and the like. Its built-in .NET tester still works, though it lacks replace/split functionality. Use it primarily as a pattern library rather than a workbench.

Visualizers

If your goal is to understand an expression rather than test inputs against it, these render patterns as diagrams:

• Regexper — https://regexper.com — turns a JavaScript regex into a railroad/syntax diagram you can export as SVG for documentation.
• Regulex — https://jex.im/regulex — another JavaScript regex visualizer.
• Debuggex (above) also doubles as a visualizer.

Worth knowing: desktop tools

For heavy or repeated work, dedicated apps go further than any web page:

• RegexBuddy — https://www.regexbuddy.com — a paid Windows app that can emulate and convert between many regex flavors; long considered the most full-featured tester available.
• Expresso — https://www.ultrapico.com/expresso.htm — a free .NET-focused Windows tool, equally usable as a teaching aid or a development environment.

A large, continually updated catalog of regex tools and libraries lives in the community-maintained awesome-regex list on GitHub.

Legacy, changed, or closed tools

The original generation of online testers leaned heavily on Flash and Silverlight, both of which browsers dropped years ago. Here's what became of the well-known older names:

• Regex Hero — changed. The original Silverlight web tester (https://regexhero.net) no longer runs in modern browsers, since Silverlight is dead. It was rebuilt as a free Windows app distributed through the Microsoft Store; it still runs the real .NET Regex library, with optional paid feature packs. For a browser-based .NET tester, use Regex Storm instead.
• Gskinner's RegExr — superseded (in a good way). The old Flash/ActionScript tool was completely rewritten as the modern HTML/JS RegExr at https://regexr.com (see above). The old Flash version is gone.
• RegexPal — still alive, now under new ownership. Steven Levithan's original JavaScript tester is now maintained by Dan's Tools at https://www.regexpal.com, supporting JavaScript and PCRE. Dan's Tools also runs a RegExr-powered tester at https://www.regextester.com.
• MyRegexTester — effectively closed. The site (https://myregextester.com) is no longer maintained and now simply points visitors to regex101 as an alternative.
• Pagecolumn's regex tester — still online but dated. The PHP/JavaScript tool at https://www.pagecolumn.com/tool/regtest.htm hasn't been meaningfully updated in many years; usable in a pinch, but the modern options above are better.
• Larsolavtorvik (regex.larsolavtorvik.com) — legacy/unmaintained. This simple PHP-PCRE/POSIX and JavaScript tester (http://regex.larsolavtorvik.com) still loads but runs on very old infrastructure (PHP 5.x) and shouldn't be relied on.
• Rextester — alive, but repurposed. https://rextester.com evolved into a general multi-language online compiler. It still has a regex page (https://rextester.com/tester) for .NET patterns, but it's no longer primarily a regex tool. Note that some of its language versions are now patron-only.

Comparison table

Quick recommendation

For everyday work, start with regex101 (best explanations and debugger) or RegExr (cleanest UI, open source). Reach for RegexPlanet when you need an uncommon engine, Debuggex or Regexper to see a pattern's structure, and the language-specific testers (Pythex, Regex Storm, PHP Live Regex, Rubular) when you must match a specific runtime exactly.