Regex Tester (Python)
Test Python regex patterns online for free with our regex tester (Python). Enter a pattern and test string to see live match highlighting, match spans, group captures, and named groups. Supports all re module functions (search, match, findall, split, sub) and flags (IGNORECASE, MULTILINE, DOTALL). Generates ready-to-use Python code. No signup required — all testing runs locally in your browser.
Test Python regex patterns using re module syntax. Enter a pattern and test string, choose a function and flags, and see live match highlighting with group details. All testing runs locally in your browser.
Why Use Our Regex Tester (Python)?
Live Python regex testing with full re module support and match visualization
Live Python Regex Testing
Test Python regex patterns instantly in your browser with live match highlighting. Our regex tester (Python) shows matches as you type — no need to run a Python script to test your pattern.
Secure Regex Tester Online
All regex testing happens locally in your browser — your patterns and test strings never leave your device. Use our regex tester (Python) online with complete privacy and zero data collection.
Regex Tester Online — No Installation
Use our Python regex tester directly in any browser with no Python installation, pip packages, or IDE required. Test regex patterns from any device, anywhere, instantly.
Full re Module Support — All Functions & Flags
Our regex tester (Python) supports all re module functions: search, match, fullmatch, findall, finditer, split, and sub. Supports all flags: IGNORECASE, MULTILINE, DOTALL, and VERBOSE. Shows match spans, groups, and named groups.
Common Use Cases for Regex Tester (Python)
Practical scenarios where our Python regex tester saves time
Data Extraction & Parsing
Python developers use our regex tester to build patterns for extracting emails, URLs, phone numbers, dates, and other structured data from text. Test and refine patterns before adding them to production scripts.
Input Validation
Backend developers use our Python regex tester to validate form inputs, API parameters, and user data. Test validation patterns for passwords, usernames, postal codes, and custom formats.
Log File Analysis
DevOps engineers and data engineers use our regex tester (Python) to build patterns for parsing log files. Test patterns against sample log lines before deploying to production log analysis scripts.
Text Processing & NLP
Data scientists and NLP engineers use our Python regex tester to build text preprocessing patterns. Test tokenization, sentence splitting, and text cleaning patterns against sample text.
Web Scraping
Web scraping developers use our regex tester to extract data from HTML and text content. Test patterns for extracting prices, product names, and other structured data from web pages.
Learning & Education
Students and developers learning Python regex use our tester to understand how patterns work. See exactly which parts of the test string match and how groups capture substrings.
Understanding Python Regex
How Python's re module works and how our tester simulates it
What is Python Regex?
Python's re module provides regular expression support using Perl-compatible regex syntax. Regular expressions are patterns used to match, search, and manipulate text. Python regex supports character classes ([a-z]), quantifiers (*, +, ?, {n,m}), anchors (^, $, \b), groups ((pattern)), named groups ((?P<name>pattern)), and lookahead/lookbehind assertions. Our regex tester (Python) simulates the remodule behavior in your browser using JavaScript's compatible regex engine.
How Our Regex Tester (Python) Works
- 1. Enter Your Pattern and Test String: Type a Python regex pattern and the test string to match against. The tester shows live match highlighting as you type. All processing happens locally in your browser — your patterns and data never leave your device.
- 2. Choose Function and Flags: Select the re module function (search, match, fullmatch, findall, finditer, split, sub) and any flags (IGNORECASE, MULTILINE, DOTALL, VERBOSE). For sub, enter a replacement string.
- 3. Review Results: See highlighted matches in the test string, match details with span positions and group captures, and the equivalent Python code to use in your scripts.
Python re Module Functions
- re.search(pattern, string): Scans through the string looking for the first location where the pattern produces a match. Returns a match object or None.
- re.match(pattern, string): Tries to apply the pattern at the start of the string. Returns a match object or None. Unlike search, it only matches at the beginning.
- re.findall(pattern, string): Returns a list of all non-overlapping matches. If the pattern has groups, returns a list of groups.
- re.split(pattern, string): Splits the string by occurrences of the pattern. Returns a list of substrings.
- re.sub(pattern, repl, string): Returns the string with all occurrences of the pattern replaced by repl. Use
\1,\2to reference groups in the replacement.
Python Regex Flags
Python regex flags modify how patterns are interpreted. re.IGNORECASE (re.I) makes the pattern case-insensitive. re.MULTILINE (re.M) makes ^ and $ match at the start and end of each line rather than the whole string. re.DOTALL (re.S) makes . match any character including newlines. re.VERBOSE (re.X) allows whitespace and comments in the pattern for readability. Multiple flags can be combined with |: re.IGNORECASE | re.MULTILINE.
Related Tools
JSON to YAML
Convert JSON to YAML format instantly - Free online JSON to YAML converter
XML to YAML
Convert XML to YAML format for configuration migration - Free online XML to YAML converter
CSV to YAML
Convert CSV spreadsheet data to YAML format - Free online CSV to YAML converter
TSV to YAML
Convert TSV tab-separated data to YAML format - Free online TSV to YAML converter
Frequently Asked Questions About Regex Tester (Python)
Common questions about Python regex patterns and the re module
A Python regex tester lets you test regular expression patterns using Python re module syntax against sample strings. Our tester shows live match highlighting, match spans, group captures, and generates the equivalent Python code — all running in your browser.
re.search() scans through the entire string looking for any location where the pattern matches. re.match() only matches at the beginning of the string. Use re.search() when you want to find a pattern anywhere in the string, and re.match() when the pattern must appear at the start.
Use (?P<name>pattern) syntax to create named groups. For example, (?P<year>\d{4})-(?P<month>\d{2}) creates groups named "year" and "month". Named groups can be accessed with match.group("year") in Python. Our tester shows named group captures in the match details.
The re.DOTALL (re.S) flag makes the . metacharacter match any character including newlines. By default, . matches any character except newline. Use DOTALL when your pattern needs to match across multiple lines.
In re.sub(), use \1, \2 to reference captured groups in the replacement string. For example, re.sub(r"(\w+) (\w+)", r"\2 \1", text) swaps two words. For named groups, use \g<name>.
re.findall() returns a list of all matches as strings. re.finditer() returns an iterator of match objects, which provide additional information like span positions and group captures. Use finditer when you need match positions or group details.
Yes! Our regex tester (Python) is 100% free with no signup, no ads, and no usage limits. Test Python regex patterns as many times as you need — completely free, forever.
Absolutely. All regex testing happens locally in your browser using JavaScript. Your patterns and test strings are never sent to any server, ensuring complete privacy.