Latest·8 min read·JSON & Data
How to Validate JSON: A Complete Guide
Validate JSON data, fix common syntax errors, and learn why validation matters for APIs and configs. Practical examples and free tools.
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30 developer guides, tutorials, and references — all free.
JSON & Data (3)Regular Expressions (3)Unix & Linux (2)Encoding & Security (7)Developer Tools (5)CSS & Web Dev (4)Web Performance (2)Text Processing (4)
·9 min read
Regular ExpressionsRegex for Email Validation: The Right Way
The correct regex pattern for email validation, why simple patterns fail, and implementation in JavaScript, Python, and PHP.
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Unix & LinuxChmod Permissions Explained: Linux Guide
Master Unix file permissions. Learn what 755, 644, and 777 mean, symbolic notation, and security best practices with an interactive calculator.
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Encoding & SecurityBase64 Encoding Explained: How It Works
What Base64 encoding is, how the algorithm works, and when to use it. Covers data URIs, JWT tokens, and API authentication with code examples.
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Encoding & SecurityHow to Create a Strong Password: The Complete Security Guide (2026)
Learn what makes a password strong, the math behind password entropy, common mistakes hackers exploit, and how to create passwords that resist brute-force attacks. Includes NIST 2024 guidelines, passphrase strategies, and free tools.
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Encoding & SecurityMD5 vs SHA-256: Which Hash to Use?
Compare MD5 and SHA-256 side by side. Differences in security, speed, output size, and when to use each for checksums and passwords.
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JSON & DataJSON vs YAML: When to Use Each Format
Compare JSON and YAML side by side. Key differences in syntax, features, and when each is better for configuration, APIs, and data exchange.
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Developer ToolsUUID v4 vs v7 vs ULID: Which to Use?
Compare UUID v4, v7, ULID, and NanoID. Differences in randomness, sortability, size, and performance for databases and APIs.
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Unix & LinuxCron Expression Syntax: Complete Guide
Master cron syntax with this guide. The 5-field format, special characters, common schedules, and examples for Linux, AWS, and Kubernetes.
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CSS & Web DevPX vs REM vs EM: CSS Unit Guide
Differences between px, rem, and em in CSS. When to use each for fonts, spacing, and responsive layouts with accessibility best practices.
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Web PerformanceWebP vs AVIF vs PNG: Format Comparison
Compare WebP, AVIF, and PNG image formats. Compression ratios, quality, browser support, and when to use each for web performance.
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Regular ExpressionsRegex Cheat Sheet: 20 Essential Patterns
20 most useful regex patterns for email, URL, phone, date, IP, and password validation. Copy-paste ready with explanations.
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Encoding & SecurityWhat is JWT? Developer's Guide
How JSON Web Tokens work: three-part structure, common claims, security best practices, and when to use JWTs vs sessions.
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Encoding & SecurityURL Encoding Explained: When You Need It
What URL encoding is, which characters need it, %20 vs +, and how to encode in JavaScript, Python, and PHP. Practical examples.
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CSS & Web DevHEX vs RGB vs HSL: Color Format Guide
Differences between HEX, RGB, and HSL. When to use each, conversion tips, and practical CSS color management advice.
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CSS & Web DevWCAG Color Contrast: Quick Guide
WCAG contrast ratio requirements for AA and AAA. How to check, fix, and design accessible color combinations for text and UI.
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Developer ToolsUnix Timestamps Explained
What Unix timestamps are, why developers use epoch time, seconds vs milliseconds, timezone pitfalls, and the Year 2038 problem.
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Text ProcessingMarkdown Cheat Sheet: Syntax Reference
Complete Markdown syntax reference: headings, bold, italic, links, images, code blocks, tables, task lists, and GFM extensions.
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Text ProcessingcamelCase vs snake_case vs kebab-case Guide
When to use camelCase, snake_case, kebab-case, PascalCase, and CONSTANT_CASE. Conventions for JS, Python, CSS, SQL, and APIs.
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Encoding & SecurityHow to Create a Strong Password
What makes a password strong, how entropy works, why length beats complexity, and modern NIST best practices with examples.
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Developer ToolsHow to Generate QR Codes: Complete Guide
Create QR codes for URLs, Wi-Fi, email, phone, and text. Static vs dynamic, sizing, design tips, and scanning troubleshooting.
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Web PerformanceImage Optimization for the Web
Reduce image sizes by 60-80% without quality loss. Format selection, responsive images, lazy loading, and Core Web Vitals tips.
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Regular ExpressionsRegex for Phone Number Validation
Regex patterns for US, UK, international, and E.164 phone numbers. Formatting variations, country codes, and regex vs libraries.
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CSS & Web DevCSS Gradients: Linear, Radial & Conic Guide
Master CSS gradients with examples. Linear, radial, conic syntax, color stops, repeating gradients, and creative design patterns.
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JSON & DataCommon JSON Errors and How to Fix Them
Fix the 10 most common JSON syntax errors: trailing commas, single quotes, unquoted keys, and unexpected tokens with examples.
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Text ProcessingHow to Compare Two Text Files: 5 Methods
Compare texts to spot every difference. Online diff tools, command-line diff, VS Code, Git diff, and programmatic comparison.
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Encoding & SecurityVerify File Integrity with Hash Checksums
Use MD5, SHA-256, SHA-512 to verify downloads. Step-by-step instructions for Windows, Mac, and Linux with examples.
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Developer ToolsSQL Formatting Best Practices
SQL formatting standards for readable queries. Indentation, keyword casing, JOIN layout, subqueries, CTEs, and team style guides.
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Text ProcessingLorem Ipsum Guide for Designers
What Lorem Ipsum is, why designers use it, when NOT to, 8 creative alternatives, and how much text you need for any design.
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Developer Tools28 Best Free Online Developer Tools
Curated list of free online developer tools: JSON formatters, regex testers, encoders, converters. Browser-based, private, no signup.
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