Write and test regular expressions with live matching.
Write a regex, paste test text, and CipherForces highlights every match in real-time. See capture groups, named groups, and all standard flags (g, i, m, s, u, y). Generate substitution previews with the replace function. Runs entirely in your browser.
(?<year>\\d{4}) displays with its name.Privacy: Regex evaluation uses the browser's native engine. Nothing is transmitted.
No. The regex tester runs entirely in your browser using JavaScript, so your pattern and test string never leave your device or reach a server. Nothing is uploaded and no signup is required. After the page loads it even works offline, which keeps sensitive text fully private.
Type your pattern in the Pattern field, toggle flags like g, i, or m, then paste sample text into the Test String box. Matches highlight instantly as you type, and the Matches tab lists each result with its index. No button press is needed; results update live.
Yes. The Groups tab shows each numbered and named capture group with its content, so you can confirm what your pattern captures. The Replace tab lets you enter a replacement using $1, $2, or $& for groups, then previews and copies the rewritten text instantly.
It runs the JavaScript regex engine, so JavaScript patterns match exactly. For Python, Go, Java, Rust, and PHP, choose that flavor to see notes on syntax differences like named groups or unsupported lookarounds, but the actual matching still uses JavaScript rules.
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