Best Free JSON Formatter & Validator Online
Our JSON formatter is the most powerful free online JSON validation and formatting tool for developers. Instantly validate JSON syntax, beautify JSON with proper indentation, minify JSON for production, view JSON in tree structure, highlight syntax errors with line numbers, and format nested JSON objects. Perfect for debugging REST API responses, validating JSON configuration files, testing JSON data in Node.js applications, formatting JSON for MongoDB databases, and working with JSON in React, Angular, or Vue.js projects. Supports large JSON files up to 10MB. Works with JSON arrays, objects, nested structures, and handles escaped characters properly.
Base64 Encoder and Decoder - Free Online Tool
Convert text, strings, and files to Base64 encoding or decode Base64 back to original format. Base64 encoding is essential for embedding images in HTML data URIs, encoding binary data in JSON APIs, transmitting files over HTTP, storing binary data in XML, encoding email attachments in MIME format, and creating data URLs for CSS. Use our tool to encode text to Base64 for URL parameters, decode Base64 authentication headers, convert images to Base64 for inline embedding, encode PDFs for API transmission, and decode Base64 strings in JWT tokens. Supports UTF-8, ASCII, binary files, images (PNG, JPG, GIF), and documents.
UUID Generator (GUID Generator) - Version 4
Generate universally unique identifiers (UUIDs) or GUIDs instantly for databases, APIs, and distributed systems. Our UUID generator creates RFC 4122 compliant version 4 UUIDs (random) that are cryptographically secure and guaranteed unique. Use UUIDs for database primary keys in PostgreSQL, MySQL, MongoDB, user IDs in authentication systems, session tokens for web applications, order IDs in e-commerce, request IDs for API logging, file names for cloud storage, and message IDs in message queues. Generate single or bulk UUIDs (up to 1000 at once). Compatible with JavaScript, Python, Java, C#, PHP, Ruby, Go, and all programming languages. Alternative to auto-increment IDs for distributed databases and microservices.
Hash Generator - MD5, SHA-1, SHA-256, SHA-512 Online
Create cryptographic hashes for password hashing, file integrity verification, and data validation. Our hash generator supports MD5, SHA-1, SHA-256, SHA-512, and other hash algorithms entirely in your browser. Use MD5 for file checksums and cache keys (not for security), SHA-1 for git commit hashes and legacy systems, SHA-256 for password hashing with bcrypt/scrypt, digital signatures, blockchain, and SSL certificates, SHA-512 for maximum security in password storage and cryptographic applications. Generate hashes for text strings, calculate file checksums, verify download integrity, create API signatures, hash passwords for storage (use with salt), and validate data consistency. All hashing happens client-side - your sensitive data never leaves your device.
Online Regex Tester - Test Regular Expressions
Build, test, and debug regular expressions in real-time with our powerful regex tester. Write regex patterns with syntax highlighting, test against multiple strings simultaneously, see all matches with group captures, get detailed match explanations, and validate regex before implementation. Essential for email validation regex, phone number formatting, URL pattern matching, form input validation, log file parsing, text extraction from HTML, data scraping, search and replace operations, and parsing CSV or structured text. Supports JavaScript regex (ECMAScript), Python regex (re module), PHP regex (PCRE), Java regex, .NET regex, and POSIX regex. Test regex flags (global, case-insensitive, multiline, unicode), use lookaheads and lookbehinds, test named capture groups, and debug complex regex patterns. Save and share regex patterns with examples.
DNS Lookup Tool - Check DNS Records Online
Perform DNS lookups to check domain name system records for any domain or subdomain. Query A records for IPv4 addresses, AAAA records for IPv6 addresses, MX records for email servers, CNAME records for domain aliases, TXT records for domain verification and SPF, NS records for nameservers, SOA records for zone authority, and PTR records for reverse DNS. Use DNS lookup to troubleshoot domain configuration, verify DNS propagation after changes, check email server setup, validate domain ownership for Google Search Console or SSL certificates, diagnose website connection issues, test CDN configuration, and audit DNS security (DNSSEC). View DNS response times, TTL values, and authoritative nameservers. Alternative to nslookup, dig, and other command-line DNS tools.
What Is My IP Address - Public IP Checker
Instantly check your public IP address, location, ISP, and browser information. Our IP checker shows your IPv4 and IPv6 addresses, geolocation (country, city, region), internet service provider (ISP), hostname, user agent, browser type, operating system, and connection type. Use it to verify VPN connection, check proxy status, troubleshoot network issues, test geolocation APIs, verify IP whitelisting, check for IP leaks, and confirm public-facing IP for server access. Useful for developers testing location-based features, system administrators managing firewalls, and users checking network security. Shows the same IP that websites see when you visit.
JSON Generator - Create Mock JSON Data
Generate realistic mock JSON data for testing APIs, prototyping applications, and populating databases. Create sample user data, product catalogs, order records, random strings, numbers, dates, email addresses, phone numbers, addresses, and nested JSON objects. Customize JSON structure with arrays, objects, primitive types, and generate bulk data (up to 1000 records). Perfect for testing REST APIs, seeding development databases, creating fixtures for unit tests, prototyping frontend applications before backend is ready, and demonstrating data structures. Export as formatted JSON, minified JSON, or copy to clipboard for immediate use in Postman, Insomnia, or code.
JSON to CSV Converter - Free Online Tool
Convert JSON data to CSV (comma-separated values) format for Excel, Google Sheets, or database import. Upload JSON file or paste JSON array of objects and get CSV output with headers. Handles nested JSON by flattening objects, converts JSON arrays to CSV rows, preserves data types, and properly escapes special characters. Use it to export API responses to spreadsheets, migrate JSON data to SQL databases, create reports from JSON logs, convert MongoDB exports to CSV, and prepare data for analysis in Excel or Tableau. Supports large JSON files and complex nested structures. Download CSV file or copy to clipboard.
Why Choose Rune Developer Tools?
Rune provides the most comprehensive collection of free online developer tools with instant results, complete privacy protection, no installation required, mobile-friendly interface, and professional-grade accuracy. Whether you need JSON formatter for API debugging, Base64 encoder for data transmission, UUID generator for databases, hash generator for security, regex tester for validation, DNS lookup for troubleshooting, IP checker for network diagnostics, JSON generator for mock data, or JSON to CSV converter for exports - Rune offers everything developers need in one place. All tools are free forever with no limitations.
Developer Tools Use Cases by Role
- Frontend Developers: Format JSON API responses; Test regex for form validation; Generate UUIDs for component keys; Encode images to Base64 for inline use
- Backend Developers: Validate JSON request/response; Hash passwords with SHA-256; Generate UUIDs for database IDs; Test API endpoints with mock JSON
- Full Stack Developers: Format and validate JSON data; Convert JSON to CSV for reports; Check DNS for deployment; Verify IP addresses
- DevOps Engineers: Check DNS records for infrastructure; Verify IP addresses for server access; Generate hashes for file integrity; Test regex for log parsing
- API Developers: Format and validate JSON schemas; Generate mock JSON test data; Create UUIDs for request IDs; Test regex for URL routing
- Mobile Developers: Encode images to Base64; Parse and format JSON API data; Generate UUIDs for device IDs; Hash data for caching
- Data Engineers: Convert JSON to CSV for analysis; Validate JSON data structures; Generate hashes for data integrity; Parse logs with regex
- Security Engineers: Generate secure hashes (SHA-256/512); Test security regex patterns; Check DNS for security records; Verify IP addresses
- QA Engineers: Generate test data with JSON generator; Validate API JSON responses; Test regex patterns for validation; Create unique test IDs
- System Administrators: DNS lookup for troubleshooting; Check public IP addresses; Generate hashes for file verification; Test server configs with regex
Supported Programming Languages and Frameworks
All developer tools support and integrate seamlessly with JavaScript (Node.js, React, Angular, Vue.js, jQuery), Python (Django, Flask, FastAPI), Java (Spring Boot, Hibernate), PHP (Laravel, Symfony, WordPress), C# (.NET, ASP.NET Core), Ruby (Rails), Go (Gin, Echo), TypeScript, Kotlin, Swift, Rust, and all other modern programming languages. Use JSON formatter with REST APIs and GraphQL, Base64 encoder in web applications, UUID generator with SQL and NoSQL databases (PostgreSQL, MySQL, MongoDB, Redis), hash generator for authentication and security, regex tester for all regex flavors, and DNS lookup for infrastructure management. Compatible with all frameworks, libraries, and development environments.