π§ͺ Live Testing
Regex Pattern
Test Text
Match Results
π Common Regex Patterns
How to Use
This regex pattern library is an essential tool for developers in daily work. It is simple to operate and fully featured. Here is the detailed usage guide:
Browse Patterns: The left sidebar category navigation lists 13 common categories. Click any category to filter the corresponding regex patterns. You can also enter keywords (such as "email", "phone") in the top search box, and the system will match and display relevant patterns in real time. All patterns have been practically verified and can be used directly in production environments.
Copy Patterns: Each pattern card contains a Copy Regex button. Click it to copy the regex to your clipboard, and a success notification will appear at the bottom of the page. You can also click the regex display area directly to manually copy it.
Live Testing: In the Live Testing section, enter or paste your regex in the Pattern box, enter your test text in the Test Text box, then click the Test Match button. The system will display all matching results in real time, including match positions, matched content, and captured group information. Click the Replace button to replace matched content with your specified string.
Quick Test: Click the Test This Pattern button on any template card, and the system will automatically fill that regex into the testing area for quick verification.
Use Cases
Regular expressions are widely used in software development and data processing. Here are some typical use cases:
Form Validation: In web development, both frontend and backend need to validate user input format. The email, phone, and ID regex patterns provided by this tool can be directly integrated into your projects to ensure user-submitted data meets expected formats, effectively preventing spam data and SQL injection attacks.
Log Analysis & Data Extraction: DevOps engineers and developers often need to extract key information from large volumes of logs. Using the date-time, IP address, and URL regex patterns from this tool, you can quickly extract access times, client IPs, and request paths from log files, significantly improving log analysis efficiency.
Data Cleaning & Formatting: Data analysts frequently need to clean non-compliant data items when processing raw data. For example, use the whitespace regex to remove extra spaces, the HTML tag regex to filter dangerous tags from rich text, and the special character regex to unify encoding formats.
Extended Knowledge
Basic Regex Syntax: . matches any character (except newline), ^ matches string start, $ matches string end, * matches 0 or more times, + matches 1 or more times, ? matches 0 or 1 time, {n,m} matches n to m times. [abc] matches any character in brackets, [^abc] matches any character not in brackets, \\d matches digits, \\w matches word characters, \\s matches whitespace.
Common Flags: g (global) match globally, i (ignoreCase) case-insensitive, m (multiline) multiline mode, s (dotAll) dot matches newlines, u (unicode) supports Unicode properties. For example /pattern/gi means global, case-insensitive matching.
Performance Tips: Complex regex patterns can cause performance issues, especially when processing long texts. Avoid nested quantifiers (like (a+)*) and patterns with heavy backtracking. For large log files, it is recommended to process in segments before applying regex matching. In JavaScript, pre-compiling regex patterns (defining regex literals outside loops) can significantly improve execution efficiency.
What is a regular expression?
A regular expression (Regex or RegEx) is a sequence of characters that defines a search pattern. It consists of normal characters and special meta-characters, used for text search, match, replace and validation operations. Widely used in form validation, log analysis, data extraction and more.
How many regex patterns does this library include?
This library includes over 100 commonly used regular expression patterns covering 13 categories: email validation, phone number validation, ID card validation, URL validation, IP address validation, number validation, date and time, postal codes, username and password, bank cards, license plates, HTML/XML tags, and general text processing.
How do I use the live testing feature?
In the Live Testing section on the right side, paste your test text into the Test Text box, then enter or paste your regex pattern into the Pattern box and click Test Match. The system will display all matching results including positions, matched content and captured groups in real time. You can also click the Test This Pattern button on any template card to auto-fill the pattern into the testing area.
Is regex a programming language?
No. Regular expressions are a pattern description language. Almost all mainstream programming languages have built-in regex support, including JavaScript, Python, Java, PHP, Go, C# and more. The regex syntax is basically consistent across languages, but there may be slight differences in advanced features such as named capture groups and Unicode properties.
Why does my regex pattern not match?
Common reasons include: (1) forgetting to add escape characters, e.g. ., * and other meta-characters need to be escaped as \\., \\*; (2) incorrect flag settings, add i flag if you need case-insensitive matching; (3) hidden characters in the string, use the testing tool to confirm the raw text content first; (4) using advanced syntax not supported by a specific language.
Can regex handle Unicode?
Yes. Modern JavaScript supports Unicode property escapes, such as \\p{L} matching any letter (including Chinese), \\p{N} matching any digit, \\p{Han} matching Chinese characters. Use the u flag, for example /\\p{Han}+/gu.
Can these regex patterns be used in production directly?
Most patterns have been practically verified and can be used directly. However, it is recommended to thoroughly test with your actual data before integrating into your project. For complex scenarios like email validation, regex only provides format-level preliminary validation, and complete verification requires additional methods such as SMTP verification.
How do I learn regular expressions?
Start with the basic syntax: first master the meaning of core meta-characters like ., *, +, ?, [], (), |, then practice with real cases. This tool provides rich common templates that can serve as learning references. Start with simple email matching and gradually master advanced features like group capturing and lookahead assertions.