Test, debug, and visualize JavaScript regular expressions in real time with group capture explanations, flags, and match highlights.
Configures pattern during client-side javascript regular expression (regex) tester & visualizer computation.
Configures flags during client-side javascript regular expression (regex) tester & visualizer computation.
Configures test string during client-side javascript regular expression (regex) tester & visualizer computation.
Configures replace pattern during client-side javascript regular expression (regex) tester & visualizer computation.
Extract protocol, hostname, port, path and query parameters with named groups
Validate and parse calendar dates with YYYY-MM-DD grouping
Match valid 0-255 octet IPv4 addresses safely
Verify that your pattern matches the expected configuration format. Load a built-in sample preset to compare structural formatting.
Check the flags setting in JavaScript Regular Expression (RegEx) Tester & Visualizer to ensure encoding, precision, or specification version matches your target runtime.
Every regular expression and test string is evaluated strictly within your browser runtime. Zero data is ever sent to servers, maintaining absolute confidentiality for API keys, logs, and sensitive payloads.
Equipped with smart execution guards, zero-width loop advancement, heuristic nested quantifier alerts, and a 250ms evaluation ceiling to keep the UI thread responsive.
Provides distinct color mapping for numbered and named capture groups, hierarchical matching indices, and live substitution preview with tokens like $1, $2, and $&.
Capture user mailbox and domain names into distinct groups
RFC 3986厳格規格、encodeURIComponent、encodeURI、formUrlEncodedに対応した高速・安全な双方向URL変換ツール。
名前付き実体参照、10進数参照、16進数参照を相互変換し、XSS攻撃を防ぎ特殊記号を正しく表示する高速エスケープツール。
POSIXエポック秒（1970年1月1日基準）の秒・ミリ秒・マイクロ秒・ナノ秒相互変換、タイムゾーン計算、ISO 8601フォーマット、2038年問題の完全ガイド。
Visual Unix file permission calculator with numeric (755, 644) and symbolic (rwxr-xr-x) modes.
Converts arbitrary JSON structures into clean, type-safe TypeScript interfaces.
camelCase、PascalCase、snake_case、kebab-case、CONSTANT_CASEなど15種類の命名規則にテキストやコード変数を瞬時に一括相互変換。