Regex Generator — Generate Regular Expression from Test Cases
Automatically generate regular expressions from sample strings. Paste your test cases, select matching options, and get a working regex pattern with live test results. Fully client-side — no data is sent anywhere.
How to Use the Regex Generator
- Paste your sample strings in the textarea — one string per line. These are the values you want to match.
- Select matching options — choose whether to match the exact pattern, or use contains, starts with, or ends with logic.
- Enable built-in patterns for common formats like emails, URLs, or numbers.
- View the generated regex — copy the pattern and flags for use in your code or search tools.
- Check the test results table to verify each sample string matches (or doesn't match) the pattern.
Why Use This Regex Generator
Writing regular expressions by hand is error-prone and tedious. Instead of guessing the right pattern, this tool learns from your actual data. Provide sample strings, and it generates a regex that matches them — no regex expertise required.
The live test results let you verify the pattern works before you put it into production code. Whether you need to validate emails, extract URLs, or match custom data formats, this generator saves time and eliminates trial-and-error debugging.
Frequently Asked Questions
Absolutely. Paste any strings — product codes, phone numbers, filenames, custom IDs, log entries — and the generator will create a pattern that matches their common structure. The "Match exact" option is the default and works for most cases.
The tool typically uses the i flag (case-insensitive) for flexibility, and g (global) for matching all occurrences. The flags are displayed alongside the pattern so you know exactly what's included.
The generator produces a good starting pattern based on your samples, but complex patterns with special characters or edge cases may need manual refinement. Always test the output against a broader set of data before relying on it in production.
Use Cases
Validating User Input
Generate regex patterns to validate emails, phone numbers, usernames, and other user-submitted data.
Log File Parsing
Create patterns to extract specific data from log files, error messages, or structured text output.
Search and Replace
Build regex for find-and-replace operations in code editors, IDEs, and text processing tools.
Data Extraction
Extract structured data like IDs, codes, or values from unstructured text using generated patterns.