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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40 developer guides, tutorials, and references — all free.
JSON & Data (3)Regular Expressions (3)Unix & Linux (2)Encoding & Security (6)Text Processing (5)Developer Tools (5)CSS & Web Dev (4)Web Performance (2)Claude Code (10)
·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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Text ProcessingHow to Convert Markdown to PDF: The Complete Guide (2026)
Five proven ways to convert Markdown files to PDF — browser-based, Pandoc CLI, VS Code, programmatic, and online converters. Compare quality, learn fixes for common issues (page breaks, code blocks, images), and pick the right method for READMEs, docs, and reports.
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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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Claude CodeWhat Is Claude Code? The Complete Guide (2026)
Claude Code is Anthropic's agentic CLI for coding in your terminal. Learn how it works, how to install it, and its core building blocks in this 2026 guide.
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Claude CodeClaude Code Agents: How to Install and Use Subagents
Learn what Claude Code subagents are, how the .claude/agents folder and frontmatter work, and how to install ready-made agents from ToolZip in one command.
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Claude CodeClaude Code MCP Servers: The Complete Setup Guide
Learn how MCP servers extend Claude Code with databases, browsers, and docs. Configure .mcp.json, pick a transport, and install servers in one command.
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Claude CodeClaude Code Slash Commands: Build Custom Commands
Learn how Claude Code slash commands work: the .claude/commands markdown format, arguments, when to use commands vs subagents, and how to install them fast.
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Claude CodeClaude Code Hooks: Automate Your Dev Workflow
Learn how Claude Code hooks run shell commands on lifecycle events to lint on save, block dangerous commands, and fire desktop notifications on their own.
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Claude CodeBest Claude Code Agents for Developers (2026)
The best Claude Code agents for developers in 2026: code reviewer, debugger, security auditor, database expert and more, each with a one-line install command.
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Claude CodeClaude Code Skills vs Agents vs Commands: The Complete Comparison
Skills vs agents vs slash commands in Claude Code, compared plainly: what each is, how it's triggered, when to use it, and how to install each one.
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Claude CodeClaude Code Slash Commands: The Complete Cheat Sheet (2026)
A practical cheat sheet for Claude Code slash commands: every built-in command in one table, plus how to build and install your own custom /commands.
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Claude CodeClaude Code vs Cursor: An Honest 2026 Comparison
A balanced look at Claude Code and Cursor in 2026: terminal agent vs AI IDE, autonomy, extensibility, when to pick each, and how to run both together.
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Claude CodeClaude Code Settings: settings.json, Permissions, and CLAUDE.md
Configure Claude Code with settings.json and CLAUDE.md: the three settings files and their precedence, the permissions allow and deny model, and project memory.
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