Developer Guides
Developer Guides &
Tool Tutorials
128 free tools. One toolkit. Deep dive into each — how it works, when to use it, and real-world examples.
Email Validation: The Complete Guide to Verifying Email Addresses
Learn how email validation works, why it matters, and how to check any address in seconds.
IBAN Validation: How to Verify Bank Account Numbers Instantly
Understand IBAN structure, country formats, and how to catch errors before they cause payment failures.
BIC/SWIFT Code Validation: Everything You Need to Know
BIC and SWIFT codes identify banks in international transfers. Learn how to validate them correctly.
International Phone Number Validation Made Easy
Phone number formats vary wildly by country. Discover how to validate them reliably for any region.
VAT Number Validation: Check EU Business Tax IDs in Seconds
VAT numbers follow country-specific formats. Learn to validate them and avoid costly invoice errors.
Address Validation: Ensure Accurate Postal Data Every Time
Invalid addresses cause failed deliveries and data quality issues. Learn how to validate postal data.
URL Validation: How to Check If Links Are Valid and Safe
Broken links and malformed URLs hurt user experience and SEO. Learn what makes a URL valid.
IP Address Validation: IPv4 & IPv6 Checking Explained
IP address formats differ between IPv4 and IPv6. Learn how to validate both quickly and correctly.
Password Strength Checker: Build Secure User Authentication
Weak passwords are a leading cause of breaches. Learn how to measure password strength and enforce policies.
JSON, YAML & XML Validation: Format Checking for Developers
A single typo in a config file can crash your app. Learn to validate JSON, YAML, and XML instantly.
CSV Validation: Catch Data Errors Before They Cause Problems
CSV files are simple but error-prone. Learn how to validate structure, encoding, and data integrity.
Credit Card Validator: How the Luhn Algorithm Detects Invalid Numbers
Learn how credit card validation works, including the Luhn algorithm, BIN ranges, and card type detection.
JWT Decoder: Inspect and Debug JSON Web Tokens Online
JWTs power modern authentication. Learn how to decode, inspect, and debug tokens without any tools.
Hash Generator: MD5, SHA-256 and More — When to Use Each
Hashing is fundamental to security and data integrity. Learn which algorithm to choose and when.
Base64 Encoding & Decoding: A Developer's Complete Guide
Base64 is everywhere in web development. Learn how it works, when to use it, and common pitfalls.
Regex Testing: Write and Debug Regular Expressions Instantly
Regular expressions are powerful but tricky. Learn how to write, test, and debug regex patterns effectively.
Cron Expression Parser: Schedule Tasks Like a Pro
Cron syntax is concise but cryptic. Learn to read, write, and validate cron expressions with confidence.
Markdown Preview: Write and Render Markdown in Real Time
Markdown is the universal format for developer docs. Learn the full syntax and preview your output live.
JSON Formatter: Beautify, Minify and Validate JSON Online
Messy JSON is hard to read and debug. Learn how to format, minify, and validate JSON data instantly.
Text Diff Tool: Compare Files and Spot Every Change
Spotting differences between text versions is tedious manually. Learn how diff tools work and speed up reviews.
HTTP Status Codes: The Complete Reference Guide
Look up any HTTP response code — from 100 to 599. Understand meanings, categories, and when to use each code.
XML Formatter: Beautify, Validate and Minify XML
Format, validate, and minify XML data with configurable indentation. Learn how XML formatting works.
SQL Formatter: Beautify and Minify SQL Queries
Format SQL queries for any dialect. Learn how SQL formatting improves readability, catches errors, and simplifies code review.
Code Formatter: Beautify and Minify HTML, CSS, JS
Format and minify HTML, CSS, and JavaScript code instantly. Learn how formatting improves readability and minification reduces file sizes.
Subnet Calculator: IPv4 CIDR, Masks and Hosts Guide
Learn how subnetting works and calculate IPv4 subnet details from CIDR notation. Network address, broadcast, hosts, and masks explained.
How to Generate Perfect Meta Tags for SEO
Create optimized meta tags, Open Graph, and Twitter Cards with live previews.
JSON Diff: How to Compare JSON Documents Structurally
Learn how JSON diffing works, why it beats plain text comparison, and how to spot every change between two documents.
TOTP Generator: Generate 2FA Codes from Secrets
Generate time-based one-time passwords (TOTP) from Base32 secrets. Parse otpauth:// URIs and manage 2FA codes securely.
What's My IP: Understanding Your IP Address & Browser Info
Learn what your IP address reveals, how to check it, and what browser information websites can see.
Complete Emoji Picker Guide for Developers
Find, copy, and use emojis with Unicode code points and HTML entities. Complete guide for web developers.
CSS Minifier Guide: Compress Stylesheets for Faster Loading
Learn how CSS minification works, what it removes, and how to reduce stylesheet file sizes for better performance.
HTML Minifier Guide: Reduce Page Size and Boost Speed
Learn how HTML minification strips whitespace, comments, and redundant attributes to shrink your web pages.
JavaScript Minifier Guide: Optimize JS Files for Production
Learn how JavaScript minification works, why it matters for performance, and how to shrink your scripts effectively.
JSON Minifier Guide: Compact JSON Data for APIs and Storage
Learn how JSON minification strips whitespace to reduce payload sizes for APIs, configs, and data storage.
YAML Formatter Guide: Format and Validate YAML Online
Learn how to format messy YAML, validate syntax, and fix common errors in configuration files.
Color Contrast Checker: WCAG AA & AAA Compliance Guide
Learn how WCAG contrast ratios work, the difference between AA and AAA levels, and tips for designing accessible color combinations.
Readability Analyzer: Understanding Flesch-Kincaid Scores
Analyze text readability with Flesch-Kincaid scoring. Learn what reading ease scores mean and how to improve your writing.
URL Parser: Understanding URL Structure and Components
Parse URLs into protocol, host, path, query parameters, and fragments. Learn URL structure, encoding, and debugging tips.
Find and Replace: A Complete Guide to Text Search and Replacement
Learn how find and replace works, when to use regex patterns, and tips for efficient text manipulation.
String Escaping: How to Handle Special Characters in Code
Understand string escaping for JSON, HTML, URL, SQL, and regex — and why it matters for security.
Whitespace Removal: Clean Up Spaces, Tabs, and Hidden Characters
Learn about different types of whitespace, when to remove them, and how to normalize text efficiently.
Text Repeater: Generate Repeated Strings for Testing and Development
Learn when and how to repeat text with custom separators for test data, placeholders, and more.
Text Cleaning: Strip HTML, Fix Encoding, and Sanitize Content
Learn text cleaning techniques for web scraping, data pipelines, and content migration.
ROT13 Encoder: Understanding the Simplest Letter Substitution Cipher
Learn how ROT13 works, why it is symmetric, and where this simple cipher is still used today.
chmod Calculator: Unix File Permissions Explained with Examples
Understand Unix file permissions, numeric notation, and common chmod values like 755, 644, and 600.
bcrypt: How Password Hashing Works and Why It Matters
Learn how bcrypt protects passwords with adaptive hashing, salt, and cost factor tuning.
HMAC: How Hash-Based Message Authentication Works
Understand HMAC signatures, key management, and how to verify message integrity with SHA-256, SHA-384, and SHA-512.
TOML Validation: Syntax Rules, Common Errors, and Best Practices
Learn TOML syntax for configuration files, common validation errors, and how it compares to YAML and JSON.
Markdown Tables: Syntax, Alignment, and Tips for Clean Documentation
Master Markdown table syntax with alignment options, escaping rules, and tips for readable documentation.
JSONPath: Query Language for Extracting Data from JSON Documents
Learn JSONPath syntax for filtering, slicing, and extracting values from complex JSON structures.
JSON Schema Validation: A Complete Guide to Schema Drafts and Rules
Validate JSON documents with JSON Schema. Learn about draft versions, composition keywords, and common patterns.
JWT Encoder: Create and Sign JSON Web Tokens for Authentication
Learn how JWTs work, understand signing algorithms, and create tokens for stateless API authentication.
Color Converter: HEX, RGB, HSL — Convert Any Color Format
Color formats vary by tool and context. Learn the differences between HEX, RGB, HSL, and how to convert.
Case Converter: camelCase, snake_case, PascalCase and More
Different coding conventions use different case styles. Learn all the formats and convert between them instantly.
URL Encoding & Decoding: Make URLs Web-Safe Instantly
Special characters break URLs. Learn how percent-encoding works and when to encode or decode your strings.
HTML Entity Encoding: Prevent XSS and Display Special Characters
Unescaped HTML is a security risk. Learn how entity encoding protects your site and renders special characters.
Slug Generator: Create SEO-Friendly URLs From Any Text
Clean URL slugs improve SEO and readability. Learn what makes a good slug and how to generate them.
Unix Timestamp Converter: Human Dates ↔ Epoch Time
Unix timestamps are standard in programming but hard to read. Learn to convert between epoch and human dates.
Number Base Converter: Binary, Hex, Octal & Custom Bases
Learn how number base conversion works and convert between binary, decimal, hexadecimal, and any base instantly.
Date Calculator: Find Days Between Dates & Add/Subtract Days
Learn how date calculations work and find the difference between dates, add days, and determine weekdays instantly.
JSON to YAML Converter: Transform Data Formats Instantly
Learn how to convert between JSON and YAML formats, understand the differences, and transform data losslessly.
How to Convert JSON to TypeScript Interfaces
Generate TypeScript interfaces or type aliases from any JSON structure automatically.
Byte Converter: Convert Data Sizes Instantly
Convert between bytes, kilobytes, megabytes, gigabytes, and more. Understand the difference between decimal (SI) and binary (IEC) units.
Aspect Ratio Calculator: Find Perfect Dimensions
Calculate aspect ratios, find missing dimensions, and explore common presets for video, photography, and web design.
Text to Binary: How Character Encoding Really Works
Understand how text is converted to binary, hexadecimal, octal, and ASCII. A practical guide for developers and students.
Morse Code: History, How It Works & Translator Guide
Learn Morse code basics, the international alphabet, and how to translate text to dots and dashes with audio playback.
Duplicate Line Remover: Clean Up Text Data Instantly
Learn how to remove duplicate lines from text, logs, and data exports to get clean, unique content.
Line Sorter: Alphabetize and Organize Text Lines Instantly
Learn how to sort text lines alphabetically, numerically, or in reverse order for clean, organized data.
Text Reverser: Reverse Strings, Words, and Lines Online
Learn how to reverse text by characters, words, or lines for data processing, puzzles, and encoding tasks.
XML to JSON Converter: Transform XML Data Instantly
Learn how to convert XML documents to JSON format, understand the structure mapping, and handle attributes, arrays, and nested elements.
YAML to JSON Converter: Transform YAML Data Instantly
Learn how to convert YAML files to JSON format, understand the syntax differences, and handle common conversion scenarios.
Markdown to HTML Converter: Transform Markdown Instantly
Learn how to convert Markdown to clean HTML, understand the syntax mapping, and handle common formatting scenarios.
HTML to Markdown Converter: Transform HTML Content Instantly
Learn how to convert HTML to clean Markdown, preserve formatting, and handle tables, links, and nested elements.
Unit Converter: Length, Weight, Temperature & More
Convert between metric and imperial units instantly. Learn about unit categories, conversion formulas, and precision handling.
Age Calculator: Exact Age in Years, Months & Days
Calculate your exact age in years, months, days, and more. Discover your zodiac sign, birth weekday, and next birthday countdown.
BMI Calculator: Calculate Your Body Mass Index
Calculate your BMI instantly with metric or imperial units. Understand BMI categories, health implications, and limitations.
Tip Calculator: Calculate Tips & Split Bills Easily
Calculate tips instantly, split bills among friends, and learn tipping etiquette for different countries and situations.
Scientific Calculator: Trig, Log, Powers & More
Use our free online scientific calculator for trigonometry, logarithms, exponents, and more. Supports degrees/radians and expression history.
Discount Calculator: Compute Sale Prices and Percentage Savings
Calculate discounts quickly. Learn about stacking discounts, reverse calculations, and smart shopping math.
Roman Numeral Converter: Rules, Conversion, and Common Uses
Convert between Roman and Arabic numerals. Learn the rules, subtractive notation, and where Roman numerals are still used.
Number to Words: Converting Digits to Written Form in Multiple Languages
Convert numbers to words in English, French, Spanish, and more. Learn about language-specific rules and use cases.
Compound Interest Calculator: Understand How Your Money Grows
Learn the compound interest formula, compare compounding frequencies, and project investment growth over time.
Loan Calculator: Understand Amortization and Monthly Payments
Calculate loan payments, understand amortization schedules, and learn how interest affects total cost.
CSV Viewer: Open and Inspect CSV Files Without Excel
You don't need Excel to read CSV files. Learn how to open, inspect, and analyze CSV data in your browser.
CSV to JSON Converter: Transform Tabular Data in One Click
APIs expect JSON, spreadsheets produce CSV. Learn how to convert tabular data to structured JSON instantly.
JSON to CSV: Export Structured Data as a Spreadsheet
JSON data is great for APIs but hard to analyze in spreadsheets. Learn how to flatten and export it as CSV.
Excel Reader: View XLSX Files Directly in Your Browser
No Excel license? No problem. Learn how to open and inspect XLSX spreadsheet files directly in your browser.
Excel to CSV: Convert Spreadsheets to Universal Format
CSV is the universal data exchange format. Learn how to convert Excel spreadsheets to CSV without software.
CSV Diff: Compare Two CSV Files and Find Every Difference
Data pipelines can introduce subtle errors. Learn how to compare two CSV files and surface every change.
PDF Tools: How to Merge, Split & Compress PDFs in Your Browser
Learn how to merge, split, and compress PDF files using client-side tools — no upload required.
CSV to SQL: Convert Spreadsheet Data to Database INSERT Statements
Transform CSV files into SQL CREATE TABLE and INSERT statements with automatic column type detection.
Password Generator: Create Unbreakable Passwords Instantly
Strong passwords are your first line of defense. Learn what makes a password secure and how to generate one.
UUID Generator: Create Unique Identifiers for Any Project
UUIDs are the standard for unique IDs in modern software. Learn the different versions and when to use each.
Random Number Generator: Truly Unbiased Numbers Online
Not all random is equal. Learn the difference between pseudo-random and cryptographically secure randomness.
Lorem Ipsum Generator: Placeholder Text for Any Design
Every designer uses Lorem Ipsum. Learn its history, variations, and how to generate the right amount fast.
QR Code Generator: Create Scannable Codes in Seconds
QR codes bridge physical and digital worlds. Learn how they work and how to generate them for any use case.
Word Counter: How to Count Words, Characters & Reading Time
Learn how word counting works and how to analyze text length, character count, and reading time instantly.
Percentage Calculator: How to Calculate Percentages Instantly
Learn how percentage calculations work and calculate discounts, increases, and ratios instantly.
How to Generate Barcodes Online
Create barcodes in CODE128, EAN-13, UPC-A, and more — download as PNG or SVG.
How to Generate Mock Data for Testing
Learn to create realistic fake data for development and testing — names, emails, addresses, and more.
CSS Gradient Generator: Create Beautiful Gradients Visually
Learn how to create stunning CSS gradients with our visual builder. Linear, radial, and conic gradients with color stops and presets.
Box Shadow Generator: Design CSS Shadows Visually
Build complex CSS box shadows with a visual editor. Multiple shadow layers, presets, and instant CSS output.
Color Palette Generator: Build Harmonious Color Schemes
Generate beautiful color palettes using color harmony rules. Complementary, analogous, triadic, and split-complementary schemes.
How to Write a Privacy Policy: A Complete Generator Guide
Generate a GDPR and CCPA compliant privacy policy for your website. Step-by-step guide with our free generator.
Word Frequency Counter: Analyze Text for Keyword Density and Patterns
Count word occurrences in any text. Learn about frequency analysis, stop words, and content optimization.
List Randomizer: Shuffle Items Fairly with Fisher-Yates Algorithm
Randomize any list of items with a proven fair algorithm. Learn about shuffling, sampling, and random ordering.
Crontab Generator: Build Cron Expressions for Scheduled Tasks
Master cron syntax for scheduling recurring tasks. Learn common patterns, pitfalls, and debugging tips.
robots.txt Generator: Control Search Engine Crawling for Your Site
Learn robots.txt syntax, create rules for search engines and AI crawlers, and avoid common SEO mistakes.
Image Compression: Reduce File Size Without Losing Quality
Learn how lossy and lossless compression work, and how to shrink images instantly in your browser.
Image Resizing: Change Dimensions with Lanczos3 Quality
Resize images to exact pixel dimensions or percentages using high-quality Lanczos3 resampling.
Image Format Conversion: PNG, JPEG, and WebP Explained
Convert images between PNG, JPEG, and WebP. Learn when to use each format for optimal results.
Image Cropping: Interactive Crop with Aspect Ratio Presets
Crop images with interactive controls and preset aspect ratios for profile photos, thumbnails, and social media.
Background Removal: AI-Powered, Private, and Free
Remove image backgrounds with AI running entirely in your browser. No upload, no signup required.
Image to PDF: Combine Images Into a PDF Document
Learn how to merge multiple images into a single PDF with custom page size, orientation, and margins.
PNG to JPG: Convert PNG Images to JPEG Online
Learn the differences between PNG and JPEG, and convert PNG images to smaller JPEG files instantly.
JPG to PNG: Convert JPEG to Lossless PNG Online
Learn why and when to convert JPEG images to lossless PNG format for editing and archiving.
Image to WebP: Convert Any Image to WebP Format
Learn about the WebP format and convert images to WebP with lossy or lossless compression.
Image to Base64: Encode Images as Base64 Strings
Learn what Base64 image encoding is, when to use it, and encode any image to a Data URI.
Add Watermark to Images: Text & Image Overlays
Learn how to add text or image watermarks to photos with adjustable opacity, position, and tiling.
Rotate & Flip Images: 90°, 180°, Custom Angle
Rotate images by any angle and flip them horizontally or vertically — free, in your browser.
Blur Images: Gaussian Blur & Pixelation Effects
Blur photos with Gaussian smoothing or pixelation effects for privacy, censoring, or design.
Favicon Generator: Create Icons for Every Browser
Generate favicons in all standard sizes from a single image with ready-to-use HTML and manifest code.
Pick Colors from Any Image: HEX, RGB & HSL
Click any pixel to extract its color in HEX, RGB, and HSL formats — build palettes from photos.
Color Palette Extractor: Pull Colors from Any Image
Extract dominant colors and full palettes from any image. Learn how the palette extractor works and when to use it.
SVG to PNG Converter: Convert Vector to Raster Online
Convert SVG vector files to high-quality PNG images at any resolution. Learn why and when to convert SVG to PNG.
HEIC to JPG Converter: Convert Apple Photos Online
Convert HEIC and HEIF photos from iPhone to universally compatible JPG or PNG. Learn about the HEIC format and conversion options.
GIF to PNG Converter: Extract Static Frame from GIF
Convert GIF images to high-quality static PNG files. Learn when and why to extract frames from animated GIFs.
Image Metadata Viewer: Read EXIF, IPTC, XMP Data
View complete image metadata including EXIF camera settings, GPS coordinates, and editing history. Learn what metadata reveals about your photos.