Regex Tester

Regular expressions (regex) are a pattern-matching language supported by virtually every programming language — used to validate email addresses, extract data from logs, find and replace complex patterns, parse structured text, and sanitise user input. A single regex can replace dozens of lines of string-processing code, but the dense syntax is notoriously difficult to write and debug correctly. This regex tester shows all matches highlighted in real time as you type your pattern, displays matched groups and their captured values, and supports all standard flags: global (g), case-insensitive (i), multiline (m), and dotall (s). Test against any target string instantly in your browser. A backend developer might use this tool to craft a pattern that pulls every IP address out of an Nginx access log before feeding those addresses into a rate-limiting script — verifying against a real sample before it runs in production. A data engineer might paste a CSV export and iteratively build a regex that captures only date and amount fields from messy, inconsistently formatted rows. Front-end developers routinely use it to fine-tune form validation rules, confirming that a phone number or postal code pattern accepts every legitimate format while rejecting bad input before the validator ships. Developers debugging API responses and log files will find the real-time feedback especially valuable, but the tool is equally useful for DevOps engineers writing pipeline filters, QA testers building test-data patterns, and technical writers who need to search-and-replace across large documentation sets. Because everything runs directly in your browser, your text never leaves your machine — no data is sent to any server, which matters when working with sensitive logs, credentials, or customer data. Paste in a production stack trace or an internal config file with complete confidence. Whether you are learning regex for the first time or stress-testing a complex lookahead assertion, this tester provides an immediate visual feedback loop that makes the notoriously opaque syntax far easier to reason about.