Developer Tools
AI Regex Generator
Generate regular expressions from plain English descriptions using AI
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Paste Your Code
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How the AI Turns a Plain English Description Into a Working Regex
Describe what you want to match the way you would explain it to a colleague, for example every email address in a support log, or dates written as MM/DD/YYYY, then press Generate Regex. Your description goes to a Llama 3.3 70B model running on Groq, which sends back three things: the raw pattern, the flags it thinks the pattern needs, and a one line explanation of what it matches. The finished expression appears as a copyable /pattern/flags string ready to paste into JavaScript, a validation rule or a search field. There is no signup step, no email wall and no generation quota, so you can reword the sentence and run it again as many times as it takes to get the pattern you actually wanted.
Testing the Generated Pattern Against Your Own Sample Text
The optional Test String box is where this stops being guesswork. Paste real looking data, a few log lines, a CSV column, a paragraph of scraped markup, and the generated pattern is applied to it straight away using the browser's own JavaScript RegExp engine. Every hit is highlighted in yellow and a counter tells you exactly how many matches were found. That instant feedback catches the classic failures: a pattern that matches nothing at all, a greedy quantifier that swallows an entire line, or an email rule that quietly skips addresses containing a plus sign. The highlighting runs locally, so reviewing results costs no extra round trip. If the highlights look wrong, sharpen the wording of your description and generate a fresh pattern.
Where the AI Runs and What Gets Sent When You Click Generate
Being straight about this matters more than a privacy badge. This is not an offline tool. When you click Generate Regex, your description and whatever sits in the Test String box are posted to an API route on this site, which forwards them to Groq's hosted Llama 3.3 70B model and returns the pattern, flags and explanation. Only the match highlighting afterwards is pure client side JavaScript. Practically, that means you should use realistic but non sensitive sample text: swap live customer addresses for example.com ones, mask real card numbers and account identifiers, and keep internal logs out of the box. The pattern you get back behaves identically on the real data once you paste it into your own codebase or editor.
Ready Made Prompts for Emails, US Phone Numbers, IPv4 and Hex Colors
Eight one click examples sit under the description box because they cover most of what people genuinely need: email addresses, US phone numbers, IPv4 addresses, hex color codes, URLs starting with https, dates in MM/DD/YYYY format, strong passwords with a minimum length plus upper case, lower case and a number, and HTML tags. Tap one to fill the box, then edit the wording before generating, which is far quicker than typing a request from scratch. The chips also work as starting templates for narrower jobs. Begin with US phone numbers and add with optional country code and dashes. Begin with HTML tags and add only opening img tags. The more specific your sentence is, the less editing the returned expression needs afterwards.
Reading the Flags and Explanation Before You Ship the Pattern
The result panel splits the output on purpose. The combined /pattern/flags string is what you copy for a JavaScript literal, while the separate Pattern and Flags cards hand you the bare expression for tools that take flags differently, such as Python re, grep or a database check constraint. Read the flags before trusting anything: a global flag changes how replace behaves, and a missing case insensitive flag is why a pattern works on one row and fails on the next. The green explanation line states in words what the expression is meant to match, which lets you tell a broken pattern apart from a correct pattern built on a badly worded request. Treat AI output as a strong first draft and test it before production.
Frequently Asked Questions
Yes. There is no account, no login, no email capture and no trial counter. Open the page, type what you want to match, and click Generate Regex. The description box, the eight example chips, the test string matcher, the explanation panel and the copy button all work on the free page, with no paywall and no limit on how many patterns you generate.
Tap the Email addresses chip under the description box, or write your own sentence such as email addresses ending in .edu. The AI returns a ready pattern, the flags to use with it, and a plain English line explaining what it matches. Paste a few sample addresses into the Test String box first so you can see which ones actually highlight.
Usually the description was too vague or the flags are wrong. Check the Flags card: without the g flag only the first match is found, and without i the pattern is case sensitive. If the flags look right, rewrite your description with the edge case spelled out, for example phone numbers with an optional +1 country code and dashes, then generate again.
The model is asked for a JavaScript regular expression, and the match preview runs on the browser RegExp engine. Most of the core syntax, character classes, quantifiers, anchors and groups, is portable to Python re, PCRE and Java. Copy the bare Pattern field rather than the /pattern/flags string for those languages, and re-check lookbehind, named groups and flag handling.
Be realistic about it. Your description and anything in the Test String box are sent to a server route that calls Groq's hosted Llama 3.3 70B model. Only the match highlighting happens locally in your browser. Use example data instead of live customer records, mask card numbers and identifiers, then run the finished pattern against real data in your own code.