Regex Tester
Test regular expressions in your browser. Live match highlighting, capture groups, and flags — free online regex tester, no upload.
Debug regular expressions without leaving your machine
Paste a pattern and a sample string to see matches and groups instantly. Useful when refining validators, log parsers, or search-and-replace rules — and the sample data never hits a server.
What you can do with it
- Validate an email or ID pattern
- Tune a regex against real examples before shipping it in code.
- Parse log lines
- Highlight captures from a sensitive log snippet locally.
How to test a regular expression
- Enter a pattern and optional flags.
- Paste a test string to see highlighted matches.
- Inspect groups in the table or copy the match list.
Test patterns without pasting secrets into a hosted tester
Log lines, API payloads, and sample PII often appear in regex debugging. A browser-local tester highlights matches and capture groups while that sample text stays on your machine — safer than public regex playgrounds when the string includes tokens or customer data.
Flags, groups, and iterative tuning
Toggle global, case-insensitive, multiline, and other flags as you refine the pattern. Inspect capture groups before you paste the expression into production code. Pair with Diff Checker when comparing before/after replacements across two blobs.
Related reading and tools
- Diff Checker — Compare strings after a regex replace dry-run.
- JSON Formatter — Pretty-print payloads you are extracting fields from.
- Developer tools — Browse the full private developer toolkit.