Online Regex Tester & Debugger - Test Regular Expressions Live
Test, validate, and debug your Regular Expressions in real-time. Checkistan's editor highlights syntax patterns, displays captured groups, and handles standard flag configurations.
✓ 100% Free & Unlimited✓ 100% Browser Local & Private✓ No Registration Required
How to use Interactive Regex Tester Online
Step 1: Enter your custom Regular Expression syntax pattern and select flags (e.g., Global, Case-insensitive).
Step 2: Paste your target test text block into the workspace panel.
Step 3: Inspect the highlighted matches and captured groups updated in real-time.
Frequently Asked Questions
What do the "g", "i", and "m" flags represent in regex?
"g" stands for global search (find all matches rather than stopping at the first), "i" for case-insensitive matching, and "m" for multi-line search anchors.
Is this tester safe for testing confidential user database data?
Absolutely. All regular expression tests run locally in your browser tab—no data is ever transmitted across the internet.
Does this tool support advanced lookahead and lookbehind groups?
Yes, it supports lookahead and lookbehind patterns as permitted by your browser's native Javascript regex engine.