Regular expression tester

The regular expression tester provides a focused environment to validate and explore patterns against a sample text. It reports full matches, captured groups, and their positions under the semantics of the host language RegExp engine. Supported flags include g, i, m, s, u, and y, and results are presented in a structured, machine-friendly format. The tool also indicates whether the pattern is syntactically valid and surfaces any syntax or runtime errors for quick iteration.
Conceptually, you input a pattern, optional flags, and a test string. The tool compiles the pattern using the engine and iterates through the string to collect all matches, capturing group contents and start/end indices. If a replacement is requested, the tool also shows the resulting text after applying the replacement to each match. Results can be copied or exported for reuse in tests or docs.
Audience and differentiators: developers debugging input validation, QA analysts creating test data, data scientists extracting fields, and students learning regex. Unique value includes real-time feedback on each match, explicit index positions, support for named capture groups, a replacement simulator, and the ability to export results as JSON for automation pipelines.
Core features and use cases: pattern input, test string input, flags, optional replacement, per-match details (text, indices, and groups), error reporting, and export options. Common tasks include validating email-like patterns, extracting numeric fields, transforming strings, and prototyping complex expressions before integrating into software.