Regex to English Explainer
Translate a regex into a sentence. AI-assisted. 10 free explanations per day.
AI-assisted explanations are usually right but not guaranteed. For load-bearing regex (security filters, data validation in production), test against real input rather than trusting the explanation alone.
What this tool does
Regular expressions are compact and powerful. They are also notoriously hard to read, even for people who write them often. This tool sends your regex to a small AI service that breaks it down piece by piece: what each group captures, what each character class matches, what the anchors and quantifiers do, and what kinds of strings would and would not match. The pattern is sent to the service for processing. Your pattern is not stored after the request completes.
How to use it
Paste your regex into the pattern box without the leading and trailing slashes (use
\d4, not /\d4/). If your regex uses flags like i
for case-insensitive or g for global, put them in the flags box. Press
Explain. The first explanation usually arrives within a few seconds. The
free tier allows 10 explanations per day per IP. Heavier use is on the roadmap.
Common use cases
- Reading a regex written by someone else (or by you, six months ago).
- Sanity-checking that a regex you just wrote matches what you intended.
- Learning regex by reading explanations of patterns you already understand the goal of.
- Documenting a regex in code review comments by pasting the explanation.
- Spotting a subtle bug, like a missing anchor that lets the pattern match a substring instead of the whole input.
Common pitfalls
- Engine differences. JavaScript, Python, PCRE, Go, and others have small differences in regex syntax (lookbehind support, named groups, character class shortcuts). The explanation assumes a modern flavor; verify against your target engine for unusual constructs.
- Greedy vs lazy quantifiers.
.*is greedy and matches as much as possible;.*?is lazy and matches as little as possible. The explanation will note which is in use; pay attention if it surprises you. - Anchors. Without
^and$, a regex matches anywhere in the string. A pattern that "looks right" may match unwanted substrings if the anchors are missing.
Frequently asked questions
- Where does my regex go when I press Explain?
- The pattern is sent to the glunty server which forwards it to Anthropic Claude for processing. glunty does not log or store your pattern; Anthropic API receives it for the duration of the request, governed by Anthropic data-usage policy (no training on API inputs by default). Treat any pattern you submit as something a third party briefly processes; do not include literal secrets inside the pattern.
- How does this compare to regex101 or RegExr?
- regex101 and RegExr are interactive testers: paste a pattern, paste test strings, see matches highlighted in real time. This tool produces narrative explanations, not match highlighting. Both are useful at different moments. Use a tester when you want to verify a regex against specific input; use this tool when you want to read what a regex does in plain English.
- Why a 10-per-day limit instead of unlimited?
- Each explanation costs a small but real amount on Anthropic API. The cap keeps the tool free without enabling automated abuse that would force a paywall. Typical human use stays well under 10 a day. If you need higher volume, the Claude API directly is straightforward and cheap (a few cents per call).
- What if the explanation seems wrong?
- AI explanations are usually right but not guaranteed. For load-bearing regex (security filters, validation in production), test against real input and trust the test results over the explanation. If the explanation contradicts what you observe, the explanation is wrong; report what you saw rather than what the model said. AI is a tool, not an authority.
- Does it handle PCRE vs JavaScript vs Python differences?
- The model assumes a modern flavor and notes when it sees a construct that varies across engines (lookbehind, named groups, possessive quantifiers, character class shortcuts). For unusual constructs, verify against your target engine documentation. The flag input helps; pass the actual flags your engine uses.
- Can I paste a regex with secret data inside?
- Do not. A regex pattern that contains a literal API key, password, or other secret should never leave your machine. Strip secrets before pasting; replace them with placeholders like SECRET or [API_KEY]. The same advice applies to any third-party tool that accepts text input.
Cite this tool
For academic, journalistic, or technical references. Pick a format:
Citations use 2026 as the publication year. Access date is left as a fillable placeholder where the citation style expects one.