# Regex Explainer

> Break a regular expression into tokens and explain each one in plain English.

A regex explainer tokenises a regular expression and describes each part in plain English — anchors, character classes, quantifiers, groups, lookarounds and back-references — so you can read a pattern someone else wrote, or confirm that yours says what you meant.

**URL:** https://convertto.tech/t/regex-explainer
**Category:** Developer Tools (https://convertto.tech/c/developer-tools)
**Privacy:** Runs entirely in the browser; no upload
**Cost:** Free, no sign-up
**Last updated:** 2026-08-01

## Key facts

- **Privacy:** Runs entirely in your browser — nothing is uploaded
- **Cost:** Free, unlimited, no sign-up

## How to use

1. Enter or paste your pattern.
2. Enter or paste your flags.
3. The result appears immediately — copy or download it.

## FAQ

### Why is my regex so slow?

Usually catastrophic backtracking — nested quantifiers such as (a+)+ force the engine to try exponentially many ways to match a failing string. A pattern that runs instantly on valid input can hang for minutes on a slightly malformed one.

### Should I use a regex to parse HTML?

No. HTML is nested and context-dependent, which a regular expression cannot express. Use a parser. Regexes are right for tokens with a fixed shape — a postcode, a timestamp, a hex colour.

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