RegexPilot
v1.3 · out now for macOS

A regex should read like a sentence.

— not look like your fr.*ak/i\n/g password.

RegexPilot is a Mac-native visual regex builder with AI. Drag blocks. Ask in English. Test against real engines.

Download for macOSBuy €19Try it below →
Free JS/TS tier · 30-day trial of all 21 flavors · €19 one-time · macOS 14+ · 18 MB core app · ~72 MB with 13 bundled regex engines + offline voice STT · no tracking by default
RegexPilot — watch the walkthrough
RegexPilot 7-minute walkthrough — click to play
No tracking by default
No telemetry or analytics. Sharing a link is always a deliberate action, never automatic.
Runs offline
Bring your own AI key, or never talk to the network.
Instant launch
Rust + Tauri native. No Electron, no startup tax.
Multi-flavor
JS · Python · Java · C# · Ruby · Go · PHP · Perl · Rust · PCRE…
Live demo

Try it right here.

The actual app, running in your browser. Drag blocks from the palette, or paste a regex into the field at the top. Click the frame to expand full-screen.

Tip · Drag any palette item onto the canvas, or hit ⌘ K to focus the pattern input.
Hand-drawn date-regex sketch on a sticky note: three boxed sub-patterns labelled YEAR (4 digits), MONTH (0[1-9] or 1[0-2]), and DAY (0[1-9] or [12] digit or 3[01]) joined by dashes.
The sketch that became RegexPilot.
Why this exists

The drawing, made live.

I found myself drawing the regex every time — on paper, on whiteboards, in the corner of a notebook. ^, a bubble for "any word character", an arrow into a group, with the English sentence scribbled underneath so I wouldn't lose what I meant.

RegexPilot is that drawing, made live. The bubbles you draw become the pattern, the arrows become the rail, and the natural-language caption you mumble to yourself sits right there in the Breakdown panel.

Built solo · Belgium · 6 months and counting
— Kristof

Visual builder

Stop decoding regex in your head.

Drag blocks from a categorised palette, connect them on a railroad track, and see a plain-English breakdown of the whole pattern while you work.

  • Drag-and-drop builder with palette categories for characters, anchors, groups, lookarounds.
  • Inspector panel for precise edits on any node without touching the source string.
  • Breakdown tree that explains every part in plain English, bidirectionally linked to the rail.
  • Undo / redo, copy / paste, drag-to-reorder — every affordance you already know.
Canvas
\b\w0 or more@
CLASSOne of:a-z1 or more
.
CLASSOne of:a-z2 or more
\b/g
Breakdown Tree
\bWord boundary.Position at the edge of a word.
\wWord.Letters, digits, underscore.
*Quantifier.Zero or more.
@Character.Matches “@”.
[Character set.One of:
a-zRange.“a” to “z”.
+Quantifier.One or more.
]
\.Escaped character.Matches “.”.
[Character set.One of:
a-zRange.“a” to “z”.
{2,}Quantifier.Two or more.
]
\bWord boundary.Position at the edge of a word.
AI + visual, together

AI drafts. You direct.

Describe a pattern in plain English and get a working draft in seconds. The visual editor is how you catch what the AI got almost right — before it ships to production.

AI is a good starting point — but it often needs tweaking. A misplaced anchor. A quantifier off by one. A character class that skips the edge case you mentioned. Without a visual editor, those are six debug loops away. With one, they're a one-drag fix.
  • Generate from a prompt — "match UK postcodes, optional space" → a draft, not a StackOverflow rabbit hole.
  • Explain any pattern — paste legacy regex, get a plain-English breakdown grouped by intent.
  • Spot the assumptions — every pill shows what it matches. If the AI assumed 4 digits when you meant 1–4, you see it immediately.
  • Authentic engines for Java, Ruby, C#, PHP — so "worked in ChatGPT" actually means "works in production".
  • Bring your own key for OpenAI, Claude, Gemini, DeepSeek, Qwen, Mistral, Groq, OpenRouter, xAI (Grok) — or any OpenAI-compatible endpoint.
  • Or run fully offline — any OpenAI-compatible local runtime works: LM Studio, Ollama, llama.cpp, or LocalAI. Point RegexPilot at the localhost port and go.
AI chat
> match UK postcodes, with or without space
Draft: ^[A-Z]{1,2}[0-9][A-Z0-9]? [0-9][A-Z]{2}$
Confidence: high
⚠ Caught on the canvas
AI used a literal space. Your test data has entries without it (M11AA). One drag: make the space optional with \s? — fixed.
Test engines
java — 18/18 matches · authentic JDK
python — 18/18 · pcre2 adapter
ruby — 18/18 · Onigmo
Languages

21 regex flavors. Authentic engines where they matter.

Every flavor routes to the real engine its production code uses — not a JavaScript polyfill pretending to be Python. Switch flavors from the toolbar; the same pattern tells you exactly what each engine does with it. Python even toggles between the stdlib re and the third-party regex module — unlocking fuzzy matching ({e<=1}), set operations ([\w--\d]), and recursive patterns ((?R)). Why it matters: 264 of 534 tested constructs behave differently across engines — and only 83 say so.

JavaScript / TypeScript

JavaScriptCore · Safari's engine

Python

CPython 3.12 — stdlib re + regex module (fuzzy, set-ops, recursion)

Java

java.util.regex (GraalVM AOT)

Scala · Kotlin · Groovy · Clojure

JVM regex (shared)

C# / .NET

.NET 9 Regex (NativeAOT)

Ruby

Onigmo 6.2.0 — statically linked, no interpreter

PHP

PCRE2 (static-php-cli)

Go / RE2

Go stdlib regexp (sidecar)

Rust

regex crate (in-process)

Perl

microperl 5.36.3 — bundled static binary, sandbox-safe

Swift

NSRegularExpression — bundled sidecar

Shell — BSD grep / sed / awk (POSIX BRE/ERE)

TRE engine — bundled static library, deterministic on all macOS installs

Elixir

Erlang :re — same engine as in-process pcre2-rust

R

TRE and PCRE2, both in-process — perl = TRUE picks PCRE2; no system R

Dart

V8 Irregexp semantics — bundled JavaScriptCore, in-process

MySQL 8

ICU-equivalent (PCRE2+UCP) — bundled in-process

PostgreSQL

Spencer ARE — bundled in-process from postgres source
  • freeJavaScript & TypeScript on the system JavaScriptCore — the engine Safari runs. No license, no install.
  • bundledSidecar binary inside the .app, or the in-process engine is bit-identical to the language's own (PostgreSQL → Spencer ARE from postgres source; MySQL → PCRE2+UCP for ICU equivalence; Elixir → libpcre2; R → TRE and PCRE2, both in-process; Dart → JavaScriptCore, the same engine its own Irregexp port implements).
Don't just build

Test and trust.

Three ways RegexPilot catches the thing you would have shipped broken.

Live match testing

Paste sample text, see every match and capture group highlighted as you build. Multi-cursor selection maps one-to-one back to the AST.

Visual replace builder

Compose the replacement as draggable pill blocks ($1, literal text, case transforms). No guessing at back-reference syntax per flavor.

Authentic engines

Your Java regex tested against real java.util.regex, Ruby against Onigmo, the engine Ruby itself embeds, C# against the .NET runtime. No polyfill surprises.

How it works

From idea to regex in three steps.

1

Drag or describe

Pick blocks from the palette and connect them, or type what you want in plain English and let AI generate a starting pattern.

2

Test and refine

Paste sample text, flip the flavor selector, watch every match light up. Tweak individual nodes in the inspector panel.

3

Export and integrate

Copy the regex, export a code snippet in your target language, send a railroad SVG to your team docs, or open it straight from VS Code.

Pattern library

A starter library, yours to extend.

50 hand-picked patterns out of the box — email, URL, IPv4/v6, ISO-8601 dates, credit cards, password rules, log parsing, stack trace lines, plus flavor-specific examples for Dart, MySQL, PostgreSQL, shell tools, Python, Java, Ruby, C#, PHP, Perl and Rust — and your own library grows alongside them.

Email address validation
^[\w.+-]+@[\w-]+\.[a-z]{2,}$
IPv4 address network
\b(?:\d{1,3}\.){3}\d{1,3}\b
ISO-8601 date parse
\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z?
Semver parse
\d+\.\d+\.\d+(?:-[\w.]+)?
Hex color validation
#?([a-f\d]{3}|[a-f\d]{6})\b
Password rule validation
(?=.*[A-Z])(?=.*\d).{8,}
Themeable

Light, dark, and every shade between.

Auto-follow macOS, pick a curated community theme, or import your own as JSON. Semantic pill colors stay intact — the theme recolors the app chrome, not the regex-kind palette.

email-validator.rxp — RegexPilot
/^\w+@[a-z]+\.[a-z]{2,}$/
gim
Start
Word1+
"@"
[a-z]1+
"."
[a-z]2+
End
Start of line, one or more word characters, literal @, one or more letters, a dot, at least two more letters, end of line.
LightDark

Drag to compare.

Default
Dracula
Catppuccin
Tokyo Night
Gruvbox
Solarized
Nord
Rosé Pine
GitHub
Works where you work

Integrations that don't make you switch apps.

VS Code extension

Select a regex and send it to the app from the editor — right-click Open in RegexPilot, or the CodeLens above the literal. Pick Edit in RegexPilot instead and the two stay in step: rebuild the pattern on the canvas and the edit lands back in your file.

Install from the VS Code Marketplace →

Copy share link

One click turns the canvas into a URL — the pattern, its flags, the flavor, and your test text with it. The recipient opens it in any browser: no install, no account, nothing to sign up for.

Post it on X, Mastodon, Slack or Discord and it unfurls into a card with the pattern itself, syntax-highlighted.

PNG / SVG export

One-click export the railroad diagram for documentation. Vector SVG for crisp docs, raster PNG for pull-request comments.

Exported railroad diagram of an ISO date pattern: three capture groups of digits — exactly 4, exactly 2, exactly 2 — separated by hyphens

date-railroad.svg4 KB vectordate-railroad.pngraster, 4x

Built in public

Roadmap.

What's shipped and what's queued. No secrets, no "coming soon" never-arrives.

Shipped in v1.3

  • Regex+ on JavaScript / TypeScript — Steven Levithan's superset of JavaScript regex, giving you atomic groups (?>…), possessive quantifiers a++, subroutine calls, and the n (named-captures-only) and x (free-spacing) flags. Compiled down to standard JavaScript, so they run on the engine already shipping. Free on every tier, including the free one (v1.3)
  • Share a pattern by link — a permalink anyone can open in the browser, with a generated preview card naming the flavor, and single-pattern JSON export for when you want to send one pattern rather than the whole library (v1.3)
  • Shell is three tools, not one — choose BSD grep, sed or awk and the engine behaves like that tool: its dialect, its quirks, and which backslash escapes it silently ignores rather than honours. Runs on a bundled TRE engine, so nothing on your machine is invoked (v1.3)
  • R runs both of its engines in-process — TRE, which base R uses by default, and PCRE2, which perl = TRUE selects. R's own POSIX character-class tables are ported, so [[:punct:]] answers exactly as R does. No system R needed, and it works on the App Store build, where it previously could not (v1.3)
  • Engine errors in plain language — when a pattern will not compile, the app says what is wrong and what to change, in all four interface languages, instead of forwarding the engine's own English. Each message is written for the engine that produced it: Perl's lookbehind limit, Java's, and PCRE2's are three different rules and now read as three (v1.3)
  • Correctness, mostly — this release is more fixes than features. Every flavor is checked construct-by-construct against the real reference engine, and the disagreements that remain are catalogued with a named cause rather than left to be rediscovered (v1.3)
  • Clearer parser error messages, and a quick-reference signpost on the canvas (v1.3)
  • VS Code extension — right-click a regex literal to open it in RegexPilot, then edit in either place and watch both stay in step. Sessions survive a window reload, and the editor shows delivery status inline (v1.2)
  • JavaScript / TypeScript now run on macOS's own JavaScriptCore — the engine Safari uses — instead of a Rust reimplementation. Full ES2024 support, including set notation like [\w&&[a-z]] and [\p{L}--[a-z]] (v1.1)
  • Visual AST builder — drag-and-drop, railroad diagram, inspector panel
  • Breakdown tree — plain-English explanation, bidirectional hover with the rail
  • Authentic engines, bundled: Java (GraalVM AOT), Ruby (Onigmo 6.2.0, statically linked — no interpreter), C# (.NET NativeAOT), PHP (static-php-cli), Python (python-build-standalone), Perl (microperl 5.36.3), Swift (NSRegularExpression), Go (Go stdlib), PostgreSQL (Spencer ARE), MySQL (ICU / PCRE2+UCP), R (TRE and PCRE2, in-process), Shell (TRE — BSD grep / sed / awk dialects). Only Dart and Elixir use a tool from your machine (dart, elixir); everything else ships inside the app
  • In-process engines: JavaScriptCore (JS / TS / Dart — the system framework), regex crate (Rust / Go / RE2), pcre2-rust (fallback when a system tool is missing)
  • 21 flavor dispatch with per-flavor syntax support — see the list below
  • Match + replace testing with live highlighting, multi-cursor, visual replace builder
  • AI chat: OpenAI, Claude, Gemini, DeepSeek, Qwen, Mistral, Groq, OpenRouter, xAI (Grok) — BYO key; plus LM Studio / Ollama / llama.cpp server / LocalAI for offline
  • Voice dictation via Whisper Tiny (offline ggml, multilingual)
  • Pattern library: 50 curated patterns across 12 flavors, folders, tags, import/export JSON
  • Code export for 21 languages (JS, TS, Python, Java, C#, PHP, Ruby, Go, Perl, Rust, Swift, Scala, Kotlin, Groovy, Clojure, Elixir, R, Dart, MySQL, PostgreSQL, Shell)
  • PNG / SVG railroad export
  • Themes: 9 community palettes + import JSON + system-follow
  • Deep links (regexpilot://), share menu, iCloud Drive-ready file format
  • AI API keys secured in macOS Keychain — persist across reinstalls, tamper-resistant
  • One upgrade prompt, not seven — selecting a paid flavor opens a single modal with a buy or start-trial choice, instead of sending you to Settings to work out what to do
Questions

Answers, before you ask.

Does a regex work the same in every programming language?

No. We ran 534 test patterns on the real engines of 16 languages: 264 come back different in at least one of them, and only 83 fail with an error — the rest silently return different matches, or none at all. That is why RegexPilot runs your pattern on the actual engine for your target language instead of approximating it in JavaScript.

Which regex flavors does RegexPilot support?

21 flavors: JavaScript, TypeScript, Python, Java, C#, PHP, Ruby, Go, Perl, Rust, Scala, Kotlin, Groovy, Clojure, Elixir, R, Dart, Swift, MySQL, PostgreSQL and POSIX shell. Each routes to the real engine its production code uses — CPython, MRI Ruby, GraalVM Java, .NET, PCRE2, RE2 and more.

Does RegexPilot work offline?

Yes. All engines are bundled inside the app and run locally. There is no account, no telemetry and no cloud calls by default — the only exception is if you explicitly create a public share link, which sends the pattern, flags, and flavor to our server. AI pattern generation is optional — bring your own API key, or run fully offline with LM Studio, Ollama, llama.cpp.

How much does RegexPilot cost?

The visual builder with JavaScript and TypeScript engines is free. A one-time €19 license unlocks all 21 flavors with their authentic engines, AI generation and an unlimited pattern library. No subscription.

Get RegexPilot v1.3

Regex you can see.

Free forever for JavaScript & TypeScript. €19 one-time unlocks all 21 flavors with authentic native engines — no subscription. Try every flavor free for 30 days. Free updates throughout v1.x; v2 owners get a 50% upgrade discount.

Download for macOSBuy €19

Also on the Mac App Store — same app, Apple handles the payment and updates.

Prefer Homebrew?brew tap kristofp/regexpilot
brew install --cask regexpilot