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Regex Expert

Lets the agent write, debug, optimize and explain regular expressions across common flavors.

Source Download skill
Repository
RightNow-AI/openfang
Stars
18,243
Licence
Apache-2.0
Files
1 file

What it does

Once installed, the agent approaches regular expressions as a specialist. It asks which regex flavor you use (Python, JavaScript, Rust, Go, PCRE, POSIX), writes patterns starting simple, explains each one in plain English, and suggests test inputs that should and should not match. It also helps find and fix slow patterns that suffer from catastrophic backtracking, and warns against misuse such as parsing HTML or JSON with regex.

Great for

  • Developers who need a regex for input validation, log parsing or text search and want an explanation with it
  • Students or analysts learning how regex patterns work step by step
  • Anyone debugging a regex that matches too much, too little, or runs slowly

Skip it if

  • Validating emails, URLs or phone numbers for production use: the skill itself says regex alone is insufficient and a dedicated library should be used
  • Parsing HTML, XML or JSON: the skill advises against regex for this, so use a real parser

Try asking

  • “Write a regex in Python that extracts ISO dates from log lines, and explain each part”
  • “Why does my JavaScript pattern (a+)+ hang on long input? Fix it”
  • “Give me a regex for IPv4 addresses and the test cases I should run against it”
  • “Simplify this Rust regex and document what it matches”
Step-by-step guide: how to use Regex ExpertInstall, first run, examples, tips and FAQs

Install in 3 steps

  1. 1

    Download the skill

    The ZIP contains the 1 original files, the Apache-2.0 licence and an attribution note.

    regex-expert.zip
  2. 2

    Add it to your agent

    Claude Code (all projects)

    mkdir -p ~/.claude/skills && unzip regex-expert.zip -d ~/.claude/skills/

    Claude Code / Agent SDK (this project only)

    mkdir -p .claude/skills && unzip regex-expert.zip -d .claude/skills/

    Claude apps (web/desktop): Settings → Capabilities → Skills → Upload skill, and choose the ZIP.

  3. 3

    Ask for the task

    No special command needed — the agent reads the skill's description and loads it when your request matches. Try one of the prompts above.

Get better results

  • Name the regex flavor and language up front, since lookaheads, named groups and Unicode support differ between engines
  • Give both sample strings that should match and sample strings that should not, so the agent can test the pattern against both
  • For final validation of emails, URLs or phone numbers, pair the pattern with a dedicated library as the skill recommends

What's inside

  • SKILL.md

Redistributed unmodified from RightNow-AI/openfang under the Apache-2.0 licence. The assessment was drafted with AI from the skill's files on 2026-10-29. Skills can instruct your agent to run code — read SKILL.md and any scripts before installing.