Regex Tester
Enter a regex pattern, flags, and input text. Toolinix will highlight matches and list them.
Common flags: g i m s u
One match per line.
Matches are highlighted.
What is a regular expression?
A regular expression (regex) is a pattern used to search, match, or extract parts of text.
This tool runs in your browser and helps you test patterns quickly without sending data to a server.
How to use the Regex Tester
- Enter your regex pattern (without surrounding slashes).
- Add flags like g (global), i (ignore case), or m (multiline).
- Paste your input text.
- See the matches list and highlighted preview.
Tips
- Use g to find all matches, not just the first one.
- Escape backslashes in some contexts (e.g. \d, \b).
- If you get an error, the pattern may be invalid for JavaScript regex.
Related guides
Learn the workflow behind this tool and what to check next.
How to clean CSV data before import
A CSV cleanup workflow for reviewing imported data, deduplicating rows, filtering records, and extracting the columns that matter.
How to debug API JSON responses
Format the response, confirm the HTTP status, validate the schema, and compare payload changes before changing application code.
Regex checks before using a pattern in production
A pattern that matches one example may still reject valid input, accept invalid input, or become slow on adversarial text.
Positive and negative cases
Test representative matches, near misses, empty values, multiline input, Unicode text, and unusually long strings.
Flags and boundaries
Verify case, global, multiline, dot-all, anchors, word boundaries, and whether the pattern must match the full value.
Capture contract
Check numbered and named groups against the code that consumes them, especially after adding optional or nested groups.
Performance risk
Avoid ambiguous nested quantifiers and test failure cases for excessive backtracking before accepting untrusted input.
Privacy and usage
Built for quick checks without an account
Toolinix tools are designed for short developer tasks: paste a safe sample, inspect the result, copy what you need, and move on.
No login required
You can use the tools without creating an account, subscribing to a newsletter, or saving a workspace.
Local when possible
Formatters, generators, encoders, and text utilities generally run in your browser. Network diagnostics may need a server-assisted lookup to check public URLs, domains, or IPs.
Keep secrets out
Do not paste production passwords, private keys, access tokens, customer records, or regulated data into online tools unless your own security policy allows it.
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