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Free Online Developer Tools

Essential utilities for software developers — JSON formatters, Base64 encoders, hash generators, regex testers, code beautifiers and much more. All browser-based.

✓ 161 Tools ⚡ Free 🔒 Private 🚫 No Login
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All Developer Tools

Showing all 161 tools

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JSON Formatter
Format, validate and beautify JSON data instantly.
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Base64 Encoder
Encode and decode Base64 strings easily.
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URL Encoder
Encode and decode URLs for safe web transmission.
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HTML Encoder
Encode and decode HTML entities instantly.
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Regex Tester
Test and debug regular expressions with live match highlighting.
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Hash Generator
Generate MD5, SHA-1, SHA-256 and SHA-512 hashes.
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CSS Minifier
Minify CSS code to reduce file size for production.
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JS Beautifier
Beautify and format JavaScript code for readability.
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HTML Formatter
Format and indent HTML markup for clean code.
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SQL Formatter
Format and beautify SQL queries for readability.
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XML Formatter
Format and validate XML documents instantly.
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YAML Validator
Validate and format YAML configuration files.
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Markdown Previewer
Preview rendered Markdown output in real time.
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Markdown to HTML
Convert Markdown text to HTML markup.
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HTML to Markdown
Convert HTML markup to clean Markdown text.
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CSS Formatter
Format and beautify CSS stylesheets.
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JS Minifier
Minify JavaScript code for production deployment.
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JSON to CSV
Convert JSON arrays to CSV spreadsheet format.
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CSV to JSON
Convert CSV data into structured JSON format.
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JSON to XML
Convert JSON data to XML format.
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XML to JSON
Convert XML documents to JSON format.
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Timestamp Converter
Convert Unix timestamps to human readable dates.
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Cron Expression Generator
Generate and explain cron job expressions.
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JWT Decoder
Decode and inspect JSON Web Token payloads.
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Color Picker
Pick colors and get HEX, RGB and HSL values.
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Diff Checker
Compare two code snippets and highlight differences.
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HTTP Status Codes
Look up HTTP status codes and their meanings.
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HTML Minifier
Minify HTML markup to reduce page weight.
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CSS Validator
Validate CSS code for errors and warnings.
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JavaScript Linter
Lint JavaScript code for common errors.
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HTML Color Codes
Browse and search HTML color names and codes.
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Hex Color Picker
Pick any color and get its HEX and RGB codes.
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ASCII Table
Browse the full ASCII character code table.
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Emoji Picker
Search and copy any emoji from a visual picker.
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Special Characters
Browse and copy HTML special characters.
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IP Address Lookup
Look up location and ISP data for any IP address.
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DNS Lookup
Perform DNS lookups for any domain name.
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Whois Lookup
Look up WHOIS registration data for any domain.
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SSL Checker
Check SSL certificate details for any website.
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Website Status Checker
Check if a website is up or down globally.
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Ping Tool
Ping any hostname or IP from your browser.
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Port Scanner
Scan open ports on any IP address or domain.
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User Agent Parser
Parse and decode browser user agent strings.
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Browser Info
View detailed information about your browser.
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Screen Resolution Tester
Test and view your current screen resolution.
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Aspect Ratio Calculator
Calculate and convert image and screen aspect ratios.
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Sprite Generator
Generate CSS sprite sheets from multiple images.
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ICO Converter
Convert images to ICO format for favicons.
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Base Converter
Convert numbers between any numeric base system.
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JSON Schema Validator
Validate JSON against a schema definition.
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GraphQL Formatter
Format and beautify GraphQL query strings.
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Curl Command Generator
Generate curl commands for API requests.
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HTTP Request Builder
Build and test HTTP requests visually.
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Webhook Tester
Test and inspect webhook payloads in real time.
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Code to Image
Convert code snippets to shareable images.
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HTACCESS Generator
Generate .htaccess rules for redirects and rewrites.
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Nginx Config Generator
Generate Nginx server configuration snippets.
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Docker Run Generator
Generate Docker run commands from parameters.
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Environment Variable Parser
Parse and format .env environment variable files.
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Git Cheat Sheet
Interactive Git commands cheat sheet reference.
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Linux Command Generator
Generate common Linux commands from descriptions.
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CSS Specificity Calculator
Calculate CSS selector specificity scores.
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Keycode Finder
Find JavaScript keycodes by pressing any key.
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Local Storage Viewer
View and manage browser localStorage data.
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Cookie Manager
View and manage browser cookies easily.
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Responsive Design Tester
Test websites at different screen breakpoints.
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CSS Grid Visualizer
Visualize CSS grid layouts interactively.
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Flexbox Playground
Experiment with CSS flexbox properties visually.
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HSL Color Picker
Pick colors using the HSL color model.
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RGBA Color Picker
Pick colors with alpha transparency using RGBA.
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CSS Color Converter
Convert between all CSS color formats.
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Contrast Checker
Check color contrast ratios for accessibility.
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Git Ignore Generator
Generate .gitignore files for any programming language.
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Package JSON Generator
Generate package.json files for Node.js projects.
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Crontab Guru
Explain and generate cron schedule expressions.
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Regex Generator
Generate regular expressions from plain English descriptions.
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CSS Variables Generator
Generate CSS custom property variable sets.
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Tailwind Config Generator
Generate Tailwind CSS config file snippets.
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Color Token Generator
Generate design token color sets in multiple formats.
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Icon Font Cheat Sheet
Browse Font Awesome and other icon libraries.
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Unicode Character Search
Search and copy Unicode characters by name.
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Entity Code Lookup
Look up HTML entity codes for special characters.
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HTTP Headers Checker
Check HTTP response headers for any URL.
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MIME Type Checker
Look up MIME types for file extensions.
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File Extension Lookup
Look up file extensions and their associated programs.
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Character Map
Browse and copy characters from Unicode blocks.
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Base64 URL Encoder
Encode URLs to Base64 URL-safe format.
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Punycode Converter
Convert internationalized domain names to Punycode.
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IDN Converter
Convert internationalized domain names to ASCII.
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Tokenizer Tool
Tokenize text into words, sentences and n-grams.
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Stemmer Tool
Apply stemming algorithms to reduce words to roots.
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N-Gram Generator
Generate n-grams from any text for NLP analysis.
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Email Validator
Validate email address format and structure.
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Credit Card Validator
Validate credit card numbers using Luhn algorithm.
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IBAN Validator
Validate IBAN numbers for European banking.
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ISBN Validator
Validate ISBN-10 and ISBN-13 book identifiers.
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EAN Barcode Validator
Validate EAN-13 barcode numbers.
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Postcode Validator
Validate postal codes for multiple countries.
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WCAG Contrast Checker
Check WCAG 2.1 color contrast compliance.
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ARIA Label Generator
Generate ARIA labels for accessible web elements.
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Screen Reader Tester
Test how content reads with screen readers.
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Focus Order Checker
Check keyboard focus order for accessibility.
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API Call Rate Calculator
Calculate API call rates and throttling limits.
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Database Index Advisor
Generate database index recommendations from queries.
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SQL Query Analyzer
Analyze SQL query complexity and performance hints.
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JSON Diff Tool
Compare two JSON objects and highlight differences.
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XML Diff Tool
Compare two XML documents and show differences.
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Markdown Table Generator
Generate Markdown tables from data inputs.
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Markdown Linter
Lint and validate Markdown syntax.
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Swagger Generator
Generate Swagger API documentation templates.
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API Response Formatter
Format and pretty-print API responses.
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Mock API Generator
Generate mock API response data for testing.
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Test Data Generator
Generate structured test data in multiple formats.
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NOSCRIPT Tag Generator
Generate noscript fallback tags for JavaScript content.
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Preload Tag Generator
Generate resource preload link tags for performance.
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Critical CSS Extractor
Extract critical above-the-fold CSS from pages.
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Lazy Load Code Generator
Generate lazy loading code for images and iframes.
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Service Worker Generator
Generate basic service worker code for PWAs.
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Web Manifest Generator
Generate web app manifest files for PWAs.
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CSP Header Generator
Generate Content Security Policy header values.
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CORS Header Generator
Generate CORS header configurations.
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Cache Control Generator
Generate Cache-Control header directives.
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Open Graph Preview
Preview how pages look when shared on social media.
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PWA Score Checker
Check PWA compliance and score for web apps.
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Web Vitals Checker
Check Core Web Vitals scores for any page.
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Page Size Checker
Check total page weight and resource sizes.
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POS Tagger
Tag parts of speech in sentences for NLP.
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Dependency Parser
Parse sentence dependency structure for NLP.
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Color Accessibility Tester
Test color combinations for WCAG accessibility.
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Font Readability Tester
Test font readability at different sizes and weights.
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Typography Preview
Preview text in different Google Fonts instantly.
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Viewport Meta Generator
Generate viewport meta tags for responsive design.
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Print CSS Generator
Generate print-specific CSS media query styles.
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JSON to Table
Visualize JSON data as an HTML table.
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Table to JSON
Convert HTML table data to JSON format.
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TOML to JSON
Convert TOML configuration files to JSON.
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INI to JSON
Convert INI configuration files to JSON format.
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Properties to JSON
Convert Java .properties files to JSON.
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Dotenv to JSON
Convert .env files to JSON format.
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JSON to Dotenv
Convert JSON config to .env file format.
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XML to YAML
Convert XML documents to YAML format.
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YAML to XML
Convert YAML files to XML document format.
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JWT Generator
Generate test JWT tokens with custom payloads.
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HMAC Generator
Generate HMAC signatures for API authentication.
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RSA Key Generator
Generate RSA public and private key pairs.
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AES Encryptor
Encrypt and decrypt text using AES encryption.
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Bcrypt Generator
Generate and verify bcrypt password hashes.
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SQL Insert Generator
Generate SQL INSERT statements from data.
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SQL Create Table Generator
Generate SQL CREATE TABLE statements.
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TypeScript Interface Generator
Generate TypeScript interfaces from JSON data.
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Zod Schema Generator
Generate Zod validation schemas from JSON.
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GraphQL Schema Generator
Generate GraphQL schemas from data structures.
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OpenAPI Spec Generator
Generate OpenAPI specification templates.
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Postman Collection Generator
Generate Postman collection JSON from API specs.
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CSS to JS Object
Convert CSS styles to JavaScript style objects.
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JS to CSS Object
Convert JavaScript style objects to CSS.
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React Props Generator
Generate React component PropTypes from JSON.
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Vue Component Generator
Generate Vue.js component boilerplate code.
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Angular Module Generator
Generate Angular module and component boilerplate.
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Webpack Config Generator
Generate Webpack configuration files.
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Babel Config Generator
Generate Babel configuration for JavaScript projects.
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About Our Developer Tools

Modern software development involves dozens of repetitive tasks that can be automated with the right tools. Helium Dock offers the most comprehensive collection of free, browser-based developer utilities available — from JSON formatting and Base64 encoding to regex testing, hash generation, and code beautification. All developer tools on Helium Dock run entirely in your browser. There is no backend — your code, data and credentials never leave your machine. This is especially important when working with sensitive data like API keys, tokens and configuration files.

Frequently Asked Questions

Are developer tools safe for sensitive data like API keys? ▾
Yes. All processing is done locally in your browser. Sensitive data like API keys never leaves your device.
Do these tools support large JSON or XML files? ▾
Yes. Tools are optimized to handle typical development workloads efficiently within browser memory limits.
Can I use these tools offline? ▾
Once a page is loaded and cached by your browser, many tools will continue to work without an internet connection.

Explore All Tool Categories

Helium Dock offers 1000+ free tools across eight categories. Explore them all:

📝 Text Tools 🖼️ Image Tools 📄 PDF Tools 💻 Developer Tools 🔍 SEO Tools 🧮 Calculators 🔄 Converters ✨ Generators