Best Free Online Developer Tools to Use in 2026
A practical, opinionated list of the best free online developer tools worth using in 2026, organized by category so you can find what you need fast.
Aug 08, 2026
Regex Tester & Visualizer
Test and debug regular expressions in real-time with match highlighting, capture groups, and detailed match information.
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- Regex Tester
Regex Pattern
/
/gm
Enter a PCRE-compatible regex pattern without delimiters.
Test Text
Match Results
No matchesEnter a pattern and test text to see matches highlighted here.
Match Details
Matches will appear here with position, group, and capture group information.
How to Use the Regex Tester
- Enter a regex pattern — Type a PCRE-compatible pattern in the input (without delimiters).
- Toggle flags — Enable
g(global),i(case-insensitive),m(multiline), and more. - Type or paste test text — The text you want to search through.
- Watch it update — Matches are highlighted in real-time with color-coded groups.
- Inspect matches — Each match shows its position, full match, and capture groups below.
Tip
Click Load Example to try a sample regex for extracting email addresses from text.
Frequently Asked Questions
What is a regular expression?
A regular expression (regex) is a sequence of characters that define a search pattern. They are used for pattern matching, text validation, search-and-replace operations, and data extraction. This tool uses JavaScript's RegExp engine which is compatible with PCRE syntax.
What do the flags mean?
g (global) — Find all matches, not just the first. i — Case-insensitive matching. m (multiline) — ^ and $ match the start/end of each line. s (dotall) — Dot matches newlines. u (unicode) — Treat pattern and text as unicode. x (extended) — Ignore whitespace and comments in the pattern.
What are capture groups?
Capture groups are parts of a pattern enclosed in parentheses (). They "capture" the matched portion so you can extract specific parts. For example, (\w+)@(\w+) captures the username and domain separately from an email.
Is this tool compatible with PHP/Laravel regex?
JavaScript's RegExp engine is broadly compatible with PCRE (PHP) syntax for most common patterns. However, some PCRE-specific features like \K, possessive quantifiers, and recursive patterns may not work. For basic to intermediate patterns, the results will be the same.
Last updated: 17 Aug 2026
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