Regex to Code Generator

Convert regex patterns into JavaScript, Python, Go, Java, or PHP code.

Pattern

Open in Regex Tester
// JavaScript
const regex = /[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}/g;
const text = "your input string";

// Test for match
if (regex.test(text)) {
  console.log("Match found");
}

// Get all matches
const matches = text.match(regex);
console.log(matches);

// Replace
const replaced = text.replace(regex, "REPLACEMENT");
console.log(replaced);

    Examples

    Generate JavaScript for ISO-like dates

    Input
    pattern: \d{4}-\d{2}-\d{2}
flags: g
language: JavaScript
    Output
    // JavaScript
const regex = /\d{4}-\d{2}-\d{2}/g;
const text = "your input string";

// Test for match
if (regex.test(text)) {
  console.log("Match found");
}

// Get all matches
const matches = text.match(regex);
console.log(matches);

// Replace
const replaced = text.replace(regex, "REPLACEMENT");
console.log(replaced);

    JavaScript receives a regex literal with the selected g flag and the standard test, match and replace operations.

    Generate Python with case-insensitive multiline flags

    Input
    pattern: \d+
flags: im
language: Python
    Output
    # Python
import re

pattern = r'\d+'
text = "your input string"

# Test for match
if re.search(pattern, text, re.IGNORECASE | re.MULTILINE):
    print("Match found")

# Get all matches
matches = re.findall(pattern, text, re.IGNORECASE | re.MULTILINE)
print(matches)

# Replace
replaced = re.sub(pattern, "REPLACEMENT", text, re.IGNORECASE | re.MULTILINE)
print(replaced)

    The Python generator keeps the pattern in a raw string and converts i and m into a bitwise combination of re constants.

    Generate Go with an inline case-insensitive flag

    Input
    pattern: https?://[^\s]+
flags: gi
language: Go
    Output
    // Go
package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`(?i)https?://[^\s]+`)
	text := "your input string"

	// Test for match
	if re.MatchString(text) {
		fmt.Println("Match found")
	}

	// Get all matches
	matches := re.FindAllString(text, -1)
	fmt.Println(matches)

	// Replace
	replaced := re.ReplaceAllString(text, "REPLACEMENT")
	fmt.Println(replaced)
}

    Go has no JavaScript-style global flag, so g is not emitted; i becomes the inline (?i) prefix in the raw string literal.

    About this tool

    Regex to Code Generator turns one regular-expression pattern into copyable starter code for JavaScript, Python, Go, Java or PHP. Enter the pattern, toggle the supported flags, choose a language tab, and the tool emits a small example containing a match check, an all-matches operation and a replacement operation.

    The templates preserve the pattern while adapting language syntax. Python flags map to re.IGNORECASE, re.MULTILINE, re.DOTALL and re.UNICODE; Go maps i, m and s into inline flags; Java maps the same concepts to Pattern constants and escapes backslashes and double quotes; PHP removes g and u from its delimiter flags. The generator also includes presets for email, URL, IPv4, US phone and hex-color patterns.

    This is a local code scaffold, not an execution or security audit. Replace the placeholder input string and replacement text, add error handling and tests, and review each language's regex flavor before shipping the generated snippet.

    How to use

    1. Enter or choose a pattern

      Type a regex into the Pattern field or select the Email, URL, IPv4, Phone (US) or Hex Color preset.

    2. Set the flags

      Toggle Global (g), Case-insensitive (i), Multiline (m), Dotall (s) or Unicode (u) to control the generated code.

    3. Choose a language

      Switch between JavaScript, Python, Go, Java and PHP to see the same pattern in that language's template.

    4. Copy and adapt

      Copy the generated snippet, replace the placeholder text and replacement, then add the validation, error handling and tests your application needs.

    Use cases

    Moving a browser regex into a backend

    Paste a pattern used in JavaScript and generate a Python, Go, Java or PHP starting point before adding the target runtime's tests.

    Bootstrapping a parsing utility

    Use the generated match, all-matches and replacement operations as a small skeleton for log, form or configuration parsing.

    Comparing regex flavor differences

    Switch language tabs to see which flags are translated, ignored or represented differently before committing to a cross-language pattern.

    Sharing a reproducible pattern with a teammate

    Copy the language-specific example into a review or issue so the pattern and its intended operations are visible together.

    Common mistakes

    Mistake:Copying the snippet without replacing "your input string" and "REPLACEMENT".

    Fix:Those values are deliberate placeholders in every template. Replace them with real input and replacement data, then add assertions for the cases your application must support.

    Mistake:Expecting the JavaScript g flag to map to every target language.

    Fix:Global matching is represented by the target API, such as Python findall or Go FindAllString. Go ignores g, while Python uses the selected operation rather than a global flag.

    Mistake:Assuming every language supports the same regex syntax.

    Fix:Review lookbehind, named groups, Unicode behavior and escaping against the target runtime before shipping; generated syntax is a starter, not a cross-language compatibility guarantee.

    Mistake:Treating generated code as production-ready validation.

    Fix:Add input limits, error handling, tests and application-specific checks. The template demonstrates operations but does not validate user input or protect against pathological patterns.

    Frequently asked questions

    References & standards

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