UD5 Toolkit
Guess the Idiom Game – Online Literal vs Figurative
See a literal illustration of an idiom and guess the phrase. Fun for English learners.
Regex to English Explainer - Online Understand Patterns
Regex to English Explainer
Decode complex regular expressions into plain English explanations. Understand each token instantly.
Common Examples
- 📧 Email Address
- 🌐 URL
- 🖥️ IPv4 Address
- 📅 Date (YYYY-MM-DD)
- 🎨 Hex Color
- 📞 Phone Number
FAQ
A regex is a sequence of characters defining a search pattern, used for string matching, validation, and extraction. It's supported in most programming languages and tools.
Use this explainer to break down patterns. Start with tokens like
\d, \w, and quantifiers. Practice with common examples like email and phone validation.\d matches any digit (0-9). Its opposite \D matches any non-digit.Greedy quantifiers (
*, +, ?, {n,m}) match as many characters as possible, while lazy quantifiers (*?, +?, ??, {n,m}?) match as few as possible.i – case insensitive, g – global match, m – multiline (^ and $ match line boundaries), s – dot matches newline, u – unicode, y – sticky.
The explainer runs entirely in your browser – no data is sent to any server. You can use it offline once the page is loaded.
English Irregular Verb Quiz – Online Past Tense Practice
Randomly given base form, type past simple and past participle. Score tracking.
JavaScript Regex Cheatsheet - Online Interactive Pattern Reference
Interactive cheatsheet for JavaScript regular expressions with live examples. Click any token to see its explanation and test it on sample text immediately.
Regex State Machine Visualizer - Online DFA Diagram
Enter a simple regular expression and see its equivalent Deterministic Finite Automaton diagram. Learn how regex engines work.
Binary Number Explainer - Online Visual Bit Representation
Enter a decimal number and see a visual breakdown of bits, place values, and bitwise operations. Learn binary easily.
Regex Injection / ReDoS Tester - Online Safe Pattern Test
Test a regular expression against malicious inputs to detect catastrophic backtracking and ReDoS vulnerabilities. Educational.
Number to Words Converter - Online Full English
Type a number and see its full English word representation (e.g., 123 → one hundred twenty‑three). Supports large numbers.
Regex Lookaround Tester - Online Experiment with Lookahead
Practice positive/negative lookahead and lookbehind. See matches highlighted live. Master advanced regex.
Unicode Property Regex Tester - Online \p{Script=Greek}
Test regular expressions with Unicode property escapes like \p{Emoji}. See matches live. Modern regex power.
Regex Catastrophic Backtracking Tester - Online Benchmark
Test a regex against long strings and measure execution time. Detect catastrophic backtracking patterns. Visual warning if slow.
Number Base Explainer - Online Learn Binary, Hex
Enter a decimal number and see detailed step‑by‑step conversion to binary, octal, and hex. For students.
Number to English Words - Online Write Out Checks
Enter any number up to trillion and get the English word representation. For filling out checks or legal documents.
Interactive Regex Cheatsheet - Online Quick Reference
An interactive reference for regular expression tokens. Click a token to see its explanation and example. Learn regex faster.
Random English Idiom Generator - Online Learn Phrases
Get a common English idiom with its meaning and example. Perfect for ESL learners. Local collection.
Regex Visualizer - Online Railroad Diagram Generator
Enter a regular expression and see a visual railroad diagram explaining the pattern. Learn and debug regex.
Homophone Checker - Online Sound‑Alike Words Tool
Type a word to see all its homophones with definitions. Avoid embarrassing mistakes (their/there/they’re). Static dictionary.
Extract URLs - Online Link & Domain Finder Tool
Pull out all URLs and links from text. Extract domains, paths, and protocols. Perfect for SEO scraping or analyzing text documents. Client-side execution.
Extract Email Addresses - Online Email Harvester Tool
Extract all email addresses from a text block using a regex pattern. Deduplicate and sort results. Handy for lead extraction. Data stays on your machine.
Find & Replace Text - Online String Replacer Tool
Perform simple or regex-based find and replace operations on text. Batch replace words, phrases, or patterns instantly. Processed locally in your browser.
RegEx Tester - Online Regular Expression Builder & Matcher
Build and test regular expressions against sample text. Real-time match highlighting, capture groups display, and flavor options. All inside your browser.