Provides an interactive environment where users can write a regular expression pattern, test it against sample strings, and view real-time match. Code never leaves your device — formatting and validation run locally in your browser.
Content reviewed October 2026 · About Toolzum
Convert between hexadecimal bytes and ASCII text. Supports custom delimiters and real-time bidirectional conversion. Code never leaves your device — formatting and validation run locally in your browser.
Encodes text or small files into Base64 strings and decodes them back with automatic MIME-type detection for binary safety. Code never leaves your device — formatting and validation run locally in your browser.
Write HTML and see a live preview rendered in a sandboxed iframe. Perfect for prototyping and testing. Code never leaves your device — formatting and validation run locally in your browser.
Analyzes your writing with real-time word count, character counts with and without spaces, sentence and paragraph counts, plus estimated reading time (200 wpm) and speaking time (150 wpm). Essential for writers, students, and SEO professionals tracking length and pacing.
Measures return on investment by comparing net gain or loss against the original cost, expressed as both a percentage and a dollar amount. Essential for marketing campaign evaluation, equipment purchase decisions, real estate investment analysis, and comparing investment opportunities.
As you type your regex pattern and test string, matches are highlighted instantly. The tool uses the JavaScript RegExp engine, so what you see is exactly how the pattern will behave in your code.
Yes. You can toggle common flags like global (g), case-insensitive (i), multiline (m), and dotAll (s) using checkboxes. The flags are applied to your pattern in real time.
Enter one pattern at a time, but you can test it against multiple sample strings. Paste different test cases to verify your regex handles all edge cases correctly.
The tool highlights matches visually. For a detailed breakdown of what each part of your pattern means, use a regex explanation tool alongside this tester.
No. Your pattern and test strings stay in your browser and are never transmitted anywhere. Everything runs locally using the regex.js library.
Yes. With the g flag the exec loop stops after 1000 matches (zero-length matches nudge lastIndex forward so it cannot hang); without g only the first match returns. The badge reads N match/matches, and AI generation costs 1 credit per use.
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