Test and debug regular expressions with real-time match highlighting
A regex tester lets you build and test regular expressions against sample text in real time. A regular expression (regex) is a pattern used to search, match, and manipulate text — finding email addresses in a document, validating a phone number format, or extracting specific data from a string. Because regex syntax is notoriously tricky, a tester that highlights matches as you type is invaluable for getting a pattern right before using it in your code.
Regular expressions are powerful but easy to get wrong — a single misplaced character changes what a pattern matches. A regex tester removes the guesswork by showing you exactly what your pattern matches in your test text, instantly. The ConvertDox Regex Tester runs entirely in your browser, highlighting matches and capture groups as you refine your expression. It's useful for developers writing validation, data extraction, or search-and-replace logic in any language that supports regex.
Build and test patterns for validating emails, phone numbers, postal codes, or passwords before adding them to a form.
Develop a pattern to pull specific values — dates, IDs, URLs — out of a block of text.
Test a pattern for find-and-replace operations in code editors or scripts before running it.
Craft expressions to match and extract fields from log files and structured text.
Experiment with patterns and see results instantly to understand how regex syntax works.
Build patterns to strip unwanted characters or normalize formatting in messy data.
Yes, completely free with no signup and no usage limits.
It uses JavaScript regular expression syntax, which is very close to the regex used in most languages. Minor differences exist between flavors, so verify advanced patterns in your target language.
Yes. The tester runs entirely in your browser — your pattern and test text are never uploaded or stored anywhere.
Common flags: g (global, find all matches), i (case-insensitive), m (multiline, ^ and $ match line starts/ends), and s (dot matches newlines). Combine them as needed.
Parentheses in a pattern create capture groups, letting you extract specific parts of each match — useful for pulling out structured data.
Common issues are forgetting to escape special characters, missing the global flag, or a small syntax error. Build the pattern step by step and watch which part breaks the match.