The Ultimate JSON Swiss Army Knife
Format, validate, and transform your JSON with desktop-grade performance — 100% client-side and secure.
Free online JSON utilities
Formatter, validator, converters, and diff — all run locally in your browser for fast, private workflows.
Free Online JSON Formatter & Beautifier
Format, beautify, and parse JSON strings instantly. Our free online JSON formatter runs 100% in your browser for maximum privacy. Try it now.
Open toolInstant JSON Validator & Syntax Checker
Validate JSON data instantly. Find syntax errors, missing quotes, and trailing commas with our free online JSON validator. 100% client-side privacy.
Open toolJSON to TypeScript Converter
Free online JSON to TypeScript converter. Instantly generate strict TS interfaces and types from JSON payloads. 100% private, runs entirely in your browser.
Open toolJSON to Zod Schema Generator
Free online JSON to Zod schema generator—fast, no ads. Build validation in-browser for Next.js & TS; nothing leaves your device.
Open toolFree Online JSON to YAML Converter
Free online JSON to YAML converter—fast, no ads. DevOps-friendly (K8s, CI); 100% browser-based, no upload for US, EU & worldwide teams.
Open toolJSON Compare
JSON Compare: client-side JSON tool. Works offline. Use with formatter and validator.
Open tool
FAQ
Is it safe to format JSON online?
Yes, provided the tool runs 100% client-side. JSON Nova processes all data locally in your browser. Your sensitive JSON payloads are never transmitted to any server, making it safe for production data.
How do I fix an 'Unexpected Token' error?
This usually points to a syntax mistake like a missing comma between objects, an extra closing bracket, or a semicolon where a comma should be. Use our 'Format / Repair' button to auto-fix common mistakes.
Why does my JSON fail when using single quotes?
The JSON standard strictly requires double quotes for keys and string values. Single quotes are common in JavaScript but invalid in JSON. Our editor highlights these errors to help you fix them instantly.
Can I convert JSON to TypeScript interfaces?
Absolutely! JSON Nova includes a built-in TypeScript generator. Just paste your JSON and select 'To TypeScript' from the Tools menu to get perfectly typed interface definitions for your project.
Is there a limit to the JSON file size?
JSON Nova uses CodeMirror 6 for editing, which helps it handle large files up to 50MB with ease. For extremely large files, it uses web workers to ensure your browser remains responsive.
Does formatting JSON change the actual content?
No. Formatting (or 'pretty-printing') only adds whitespace and indentation to make the data human-readable. The underlying data structure and values remain exactly the same as the original input.
Does JSON Nova support XML to Class conversion?
Yes! Our 'Data to Class Hub' supports both JSON and XML source formats. You can convert XML schemas directly into Java classes, Rust structs, Go models, and many other professional programming formats.
Which programming languages are supported?
We support over 18+ major programming languages, including Java, Python, Rust, Go, C#, Swift, C++, TypeScript, Kotlin, Ruby, Dart, Haskell, Elm, Flow, Objective-C, and more. Each target uses idiomatic naming conventions and serialization attributes.
How is Null Safety handled in generated code?
Our generators are designed for professional use. We use language-specific features like Optional in Java, Option<T> in Rust, Maybe in Haskell/Elm, and Nullable types in C# and Kotlin to ensure your models are safe and robust.