Extract order IDs, verify SKUs, or test a new regular expression without sending the sample text to a server.
Never paste production passwords, live JWT access tokens or private customer records.
No uploads, cookies, tracking or third-party scripts. Your input stays in browser memory.
Ready. Enter a test value.
A seemingly simple regex can match the wrong rows, silently skip capture groups, or freeze an editor on pathological input. This tester shows each match, its text offsets, numbered and named groups, a non-destructive replacement preview, and a separate worker deadline.
Enter a JavaScript regular expression without enclosing slashes, select supported flags, and paste disposable sample text. Run the test and inspect the match list and highlighted spans. This deliberately runs the JavaScript engine, not PCRE, Python, Rust or .NET syntax.
Potentially expensive expressions execute in a dedicated Web Worker with a bounded timeout. Results are capped at 100 matches and test input at 32,000 characters. No matches prove only that this test text didn't match—not that a pattern is safe for all inputs.
No. It uses the browser JavaScript RegExp engine; Python named capture syntax and lookbehind availability differ. Test production expressions in the actual target runtime.
An isolated worker is terminated after a short deadline. This reduces the chance that a pathological pattern freezes the main page; it is not a security analysis of regular expressions.
No. The tester creates a separate preview. Your pasted test text remains unchanged until you edit or clear it.