Free Regex Tester – Real-Time Regular Expression Debugger
The NexVaani Regex Tester helps software engineers, web scrapers, and data analysts build and validate regular expressions. Test complex regex patterns against sample test strings with real-time match highlighting, capture group inspection, and flag toggles.
The NexVaani Regex Tester evaluates regular expressions in real-time against test strings using the browser native JavaScript RegExp engine with complete privacy.
Smart 1-Click Workflow Chains (Next Steps):
Real-World Use Cases & Applications
- Validating form inputs (emails, URLs, phone numbers, credit cards) before frontend implementation.
- Testing regex search patterns for log parsing and data extraction scripts.
- Debugging capture groups and named capture groups for string replacement routines.
NexVaani ツールの透明性
処理場所、ネットワーク動作、データ保持の技術的な説明
対応ツールはクライアントサイド技術によりWebブラウザー内でローカル実行されます。
計算やテキスト変換はブラウザー内でローカルに実行されます。
一時処理データはブラウザー内で処理され、NexVaaniには保存されません。
エクスポートされたファイルに透かし、スタンプ、ブランド表示は追加されません。 Output quality depends on your source file and selected settings.
使い方 Regular Expression Tester （ステップごと）
Enter Regular Expression
Type your regex pattern (e.g. ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$).
Set Regex Flags
Toggle g (global), i (ignore case), or m (multiline) flags.
Enter Test String
Paste sample text to test your pattern against.
Inspect Matches & Groups
Review highlighted matches and capture group coordinates.
技術アーキテクチャと実行の仕組み
Deterministic Finite Automata & RegExp Engine
JavaScript RegExp utilizes a backtracking Nondeterministic Finite Automaton (NFA) engine. The tester executes the pattern in a protected local execution scope, compiling tokens into character classes, quantifiers, lookaheads, and capture group slots.
Matches = Array.from(Test_String.matchAll(new RegExp(Pattern, Flags)))技術的な制限と運用上の制約
- Catastrophic backtracking patterns (e.g. nested ambiguous quantifiers (a+)+) on very long text may freeze browser threads.
主な仕様と機能
- Live Real-Time Highlighting – Matches highlight immediately as you type
- Capture Group Breakdown – Inspect full match strings and individual capture groups
- Regex Flag Toggles – Toggle global (g), case-insensitive (i), multiline (m), dotAll (s), and unicode (u)
- Pattern Error Detection – Displays syntax error messages for invalid regex syntax
よくある質問と回答
Which regex flavor does this tool use?
It uses the standard ECMAScript (JavaScript) RegExp engine built directly into your web browser.
Can I test multiline regex patterns?
Yes! Toggle the m flag to allow ^ and $ to match start and end of individual lines.
Are my files uploaded, analyzed, or stored on NexVaani servers?
Where supported, tool inputs and files are processed locally inside your web browser using WebAssembly and HTML5 Canvas. Your files are not uploaded to NexVaani file-processing servers.
評価 Regular Expression Tester
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