FreeFormatter
JSONLint
JSONFormatter.org
CodeBeautify
Code Beautify JSON Validator
ExtendsClass JSON Formatter
JSON Formatter & Validator
10015.io
WhiteKit.dev
JSONFormatter.org
Code Beautify JSON Validator
CyberChef
IT Tools
CodeBeautify
CodeSwissKnife
DevsBox
WhiteKit brings together 55 developer tools in one place: formatters (JSON, XML, SQL, YAML), converters, security utilities (JWT, hashing, encoding), network calculators, and text tools.
Everything runs 100% client-side. Your data never leaves your device, so you can safely paste API keys, tokens, and production payloads. No sign-up, no upload step, and it keeps working offline once loaded.
Each tool is built to handle real edge cases rather than just the happy path โ the cron parser implements Quartz 6-field semantics correctly, the IPv6 ULA generator follows RFC 4193 Appendix A, and the subnet calculator handles /31 and /32 edge cases.
FreeFormatter
WhiteKit.devJSONLint - JSON Lint is a web based validator and reformatter for JSON, a lightweight data-interchange format.
JSONFormatter.org - Online JSON Formatter and JSON Validator will format JSON data, and helps to validate, convert JSON to XML, JSON to CSV. Save and Share JSON
Code Beautify JSON Validator - Code Beautyโs JSON Validator or JSON Lint is easy to use tool to copy, paste and validate JSON data.
CodeBeautify - Online Tools like Beautifiers, Editors, Viewers, Minifier, Validators, Converters for Developers: XML, JSON, CSS, JavaScript, Java, C#, MXML, SQL, CSV, Excel
CyberChef - The Cyber Swiss Army Knife
IT Tools - IT Tools is a free and open-source collection of handy online tools for developers & people working in IT.