Regex Explainer

How to use

1. 1Paste a regex literal in the form /pattern/flags, or just the pattern on its own.
2. 2Read the token breakdown panel: each chip shows the source slice, a label, and a plain English explanation of what that piece of the pattern matches.
3. 3Check the Flags panel for what each active flag (g, i, m, s, u, y, d, v) changes about matching behavior.
4. 4Look at the Groups panel to see the total capture-group count and any named groups available for backreferences or replacements.
5. 5Use Copy regex literal or Copy full explanation, or click a sample to load common patterns like email, URL, hex color, or strong password.

About this tool

Regex Explainer parses any JavaScript-style regular expression and produces a numbered, token-by-token plain English breakdown so you can understand exactly what a pattern does before you ship it. Paste a full literal like /pattern/flags or just a bare pattern: the tool splits the input, recognizes every common construct (literals, escapes, character classes, anchors, alternation, groups, quantifiers, lookaheads, lookbehinds, named captures, backreferences, Unicode escapes, and Unicode property escapes), and renders each as a labeled chip with a one-sentence explanation. The flags panel describes every active flag (g, i, m, s, u, y, d, v) and flags any unknown or duplicated flag characters. A capture-group summary shows the total number of groups and lists the named ones. The pattern is also handed to the native RegExp constructor so any compile error surfaces with the engine's own message. Quick samples cover real-world patterns developers reach for: email-like strings, ISO dates with named captures, URLs, hex colors, strong password rules with lookaheads, and IPv4 octets. Parsing runs entirely in the browser; the pattern you paste is never uploaded.

Free to use. Works in your browser. No signup, no login.