# Regex Builder

> Turn a plain-language description of what to validate or extract into a regular expression with a part-by-part explanation. Use when the user wants a regex, wants to understand a regex, or wants extraction/validation patterns.

- Skill: `kroshank/regex-builder` (Agent Skill)
- Install (CLI): `npx skillmds@latest add kroshank/regex-builder`
- Raw SKILL.md: https://api.skillmd.com/api/skills/kroshank/regex-builder/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: KRoshanK (https://skillmd.com/u/kroshank)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/kroshank/regex-builder

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# Regex Builder with Explanation

Build an expression the user can maintain.

## Process
1. Restate the match goal and the non-goals.
2. Ask (or assume explicitly) flavor: JS / PCRE / Python / Go / Rust.
3. Decide: validate full string vs find/extract.
4. Write the regex. Prefer readable over clever.
5. Explain each group.
6. Give match and non-match examples.
7. Note what regex is a bad tool for (emails, HTML, nested markup) and offer an alternative when relevant.

## Output
- Flavor + flags
- Pattern
- Group map
- Examples
- Failure modes

## Rules
- No cargo-cult email regex that rejects valid addresses unless the user wants a practical filter and you label it as such.
- Escape correctly for the host language string if asked.