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Regex Patterns: The Ultimate Reference
cheatsheets

Regex Patterns: The Ultimate Reference

Common regex patterns with explanations, from email validation to password rules to URL parsing.

.gitignore Patterns: What to Exclude from Your Repository
devops

.gitignore Patterns: What to Exclude from Your Repository

Write effective .gitignore files — patterns, common templates, and the files you should never commit.

URL Encoding: Why %20 Appears in Your URLs
web-development

URL Encoding: Why %20 Appears in Your URLs

Understand URL encoding — which characters need escaping, why browsers do it, and how to encode/decode properly.

Cron Expressions: Schedule Tasks Like a Pro
devops

Cron Expressions: Schedule Tasks Like a Pro

Master cron syntax for automated task scheduling — from basics to advanced patterns.

Base64 Encoding: What It Is and How to Use It
encoding

Base64 Encoding: What It Is and How to Use It

Everything you need to know about Base64 — encoding, decoding, data URIs, and when NOT to use it.

SHA-256 Hashing: How It Works and When to Use It
security

SHA-256 Hashing: How It Works and When to Use It

Understand SHA-256 hashing — how it produces fixed-length digests, why it's irreversible, and where it's used in real systems.

Spinner Wheel: Make Random Decisions the Fun Way
fun

Spinner Wheel: Make Random Decisions the Fun Way

Create custom spinner wheels for random selection. Perfect for classrooms, team decisions, giveaways, and breaking deadlocks.

CSS Minification: A Performance Quick Win
formatting

CSS Minification: A Performance Quick Win

Compress your CSS files for faster page loads — what gets removed, how much you save, and when it matters.

JWT Tokens: Decode and Understand Your Tokens
security

JWT Tokens: Decode and Understand Your Tokens

Inspect JWT tokens to debug authentication issues — understand the header, payload, and signature.

Linux Terminal: 50 Essential Commands
cheatsheets

Linux Terminal: 50 Essential Commands

The most used Linux commands for developers and sysadmins — organized by category with real examples.

First Million Calculator: How Long to Reach Your Goal?
finance

First Million Calculator: How Long to Reach Your Goal?

Find out how long it takes to save your first million with different investment strategies. Realistic scenarios with compound interest.

CPF and CNPJ Generator: Valid Numbers for Testing
dev-reference

CPF and CNPJ Generator: Valid Numbers for Testing

Generate valid CPF and CNPJ numbers for software testing. Understand the validation algorithm and why test data matters.

Savings Simulator: The Power of Compound Interest
finance

Savings Simulator: The Power of Compound Interest

Simulate your savings growth with compound interest. See how regular contributions and time can build wealth.

Fraction Calculator: Add, Subtract, Multiply, and Divide Fractions
finance

Fraction Calculator: Add, Subtract, Multiply, and Divide Fractions

Master fraction arithmetic with step-by-step explanations. Calculate with fractions, mixed numbers, and simplify results instantly.

List Sorter: Organize Text Lists Alphabetically or Numerically
text

List Sorter: Organize Text Lists Alphabetically or Numerically

Sort any text list alphabetically, numerically, or in reverse order. Remove duplicates and clean up messy lists instantly.

Rule of Three Calculator: Solve Proportions Instantly
finance

Rule of Three Calculator: Solve Proportions Instantly

Learn how to use the rule of three to solve proportions in everyday life, cooking, finance, and programming.

WhatsApp Link Generator: Create Click-to-Chat Links
generators

WhatsApp Link Generator: Create Click-to-Chat Links

Generate WhatsApp click-to-chat links for your business. Let customers message you directly without saving your number first.

Receipt Generator: Create Professional Receipts Online
documents

Receipt Generator: Create Professional Receipts Online

Generate professional receipts for payments, services, and freelance work. No software needed, create and download instantly.

Online Notepad: Quick Notes Right in Your Browser
fun

Online Notepad: Quick Notes Right in Your Browser

Take quick notes without any app installation. Your browser becomes a lightweight, distraction-free notepad with auto-save.

Lottery Number Generator: Get Random Picks Instantly
fun

Lottery Number Generator: Get Random Picks Instantly

Generate random lottery numbers for Mega-Sena, Powerball, EuroMillions, and more. Learn how lottery probability works.

CSR Decoder: Understanding SSL Certificate Signing Requests
crypto

CSR Decoder: Understanding SSL Certificate Signing Requests

Decode and verify CSR (Certificate Signing Request) files. Learn what's inside a CSR and how SSL certificate issuance works.

Dice Roller: Generate Random Numbers for Tabletop Games
fun

Dice Roller: Generate Random Numbers for Tabletop Games

Roll virtual dice for D&D, board games, and more. Learn about dice notation, probability, and how random number generation works.

Random Number Generator: Ranges, Distributions, and Use Cases
generators

Random Number Generator: Ranges, Distributions, and Use Cases

Generate random numbers with custom ranges and learn about true vs pseudo randomness, distributions, and cryptographic security.

Internet Speed Test: How to Check Your Connection Speed
network

Internet Speed Test: How to Check Your Connection Speed

Test your internet speed and understand what download, upload, and ping numbers actually mean for your daily use.

Keyboard Shortcuts Every Developer Should Know
dev-reference

Keyboard Shortcuts Every Developer Should Know

Master keyboard shortcuts for VS Code, browser DevTools, terminal, and OS. Boost your development speed dramatically.

Temperature Converter: Celsius, Fahrenheit, and Kelvin Explained
converters

Temperature Converter: Celsius, Fahrenheit, and Kelvin Explained

Convert between Celsius, Fahrenheit, and Kelvin instantly. Learn the formulas, history, and practical applications of each temperature scale.

Unicode Escape Sequences: Handle Special Characters in Code
encoders

Unicode Escape Sequences: Handle Special Characters in Code

Learn how Unicode escape sequences work across programming languages. Convert characters to and from escape notation.

PIX QR Code: How Brazil's Instant Payment System Works
crypto

PIX QR Code: How Brazil's Instant Payment System Works

Learn how PIX QR codes work for instant payments in Brazil. Generate static and dynamic PIX codes for your business or personal use.

ASCII Art Generator: Turn Text into Creative Art
text

ASCII Art Generator: Turn Text into Creative Art

Generate ASCII art from text with different fonts and styles. Learn about ASCII art history and its surprising modern uses.

BMI Calculator: Understanding Body Mass Index
math

BMI Calculator: Understanding Body Mass Index

Calculate your BMI instantly and understand what the numbers mean. Learn about BMI categories, limitations, and when to use other health metrics.

QR WiFi: Share Your Network Password with a Scan
generators

QR WiFi: Share Your Network Password with a Scan

Generate QR codes that connect devices to WiFi automatically. No more spelling out passwords to guests.

Countdown Timers: Never Miss a Deadline or Event Again
date-time

Countdown Timers: Never Miss a Deadline or Event Again

Create countdown timers for product launches, deadlines, events, and more. Learn how countdowns work and boost your time management.

Image Resize and Crop: Edit Images Online for Free
media

Image Resize and Crop: Edit Images Online for Free

Resize and crop images directly in your browser. Learn about image dimensions, aspect ratios, and optimization for web and social media.

Days Between Dates: Calculate the Exact Difference
date-time

Days Between Dates: Calculate the Exact Difference

Need to know exactly how many days between two dates? Learn the math behind date calculations and use our free tool for instant results.

Image Grayscale: Convert Photos to Black and White Online
media

Image Grayscale: Convert Photos to Black and White Online

Convert any image to grayscale instantly in your browser. Learn how grayscale conversion works and when to use black and white images.

Business Days Calculator: How to Exclude Weekends and Holidays
date-time

Business Days Calculator: How to Exclude Weekends and Holidays

Learn how to calculate business days accurately by excluding weekends and holidays. Essential for project planning, deadlines, and contractual obligations.

Word Cloud Generator: Visualize Text Data Instantly
text

Word Cloud Generator: Visualize Text Data Instantly

Create beautiful word clouds from any text. Learn how word frequency visualization works and where to use it effectively.