JSON to TOML Converter
JSON Input
TOML Output
About JSON to TOML Converter
TOML (Tom's Obvious Minimal Language) is a configuration file format that's easy for humans to read and write. This tool converts JSON data to TOML format, which is popular in Rust projects (Cargo.toml), Python packaging (pyproject.toml), and modern build tools. TOML is designed to be more readable than JSON for configuration files while being unambiguous and easy to parse. It uses a simple key-value format with sections (tables) for nested data. The conversion preserves your data structure including nested objects, arrays, strings, numbers, booleans, and null values. TOML is less verbose than JSON and YAML, making it perfect for configuration files. Perfect for converting JSON configs to TOML for Rust projects, creating pyproject.toml files for Python projects, migrating from JSON to TOML configs, or working with modern build tools. All conversion happens in your browser for complete privacy.
How to Use
- Paste or type your JSON data in the left panel.
- The TOML output will appear automatically on the right.
- Your JSON must be an object at the root level (not an array).
- Click "Copy" to copy the TOML to your clipboard.
- Click "Download" to save the TOML as a .toml file.
- Use "Clear" to reset both input and output.
- The tool handles nested objects, arrays, and all JSON data types.
Frequently Asked Questions
What is TOML?
TOML (Tom's Obvious Minimal Language) is a configuration file format created by Tom Preston-Werner (co-founder of GitHub). It's designed to be easy to read and write due to obvious semantics. TOML is popular in Rust (Cargo.toml), Python (pyproject.toml), Hugo static sites, and various DevOps tools.
When should I use TOML instead of JSON or YAML?
Use TOML for configuration files where readability and simplicity matter. TOML is more readable than JSON (no brackets/quotes clutter), less complex than YAML (no indentation ambiguity), has clear types and unambiguous syntax, and is perfect for application configs, package manifests, and build tool configurations. It's the standard for Rust and Python projects.
Why must my JSON have an object at the root?
TOML files always start with key-value pairs or tables (sections). They cannot start with an array at the root level. If your JSON is an array, wrap it in an object like {"items": [...]}, then convert it to TOML.
How are nested objects converted?
Nested objects become TOML tables (sections). For example, {"database": {"host": "localhost"}} becomes [database] followed by host = "localhost". Deeply nested objects create dotted table names like [database.connection.pool].
How are arrays handled?
Simple arrays (strings, numbers, booleans) become TOML arrays: servers = ["alpha", "beta"]. Arrays of objects can become inline tables or array-of-tables syntax depending on complexity. Empty arrays become [].
What happens to null values?
TOML doesn't have a native null/undefined concept. Null values are converted to empty strings (""). If you need to represent absence of a value in TOML, you typically omit the key entirely or use an empty string.
Can I convert complex nested JSON?
Yes! This tool handles deeply nested objects, arrays at any level, mixed data types, and complex structures. However, very deeply nested or highly dynamic structures might be better suited for JSON or YAML rather than TOML.
What's the difference between TOML and INI files?
TOML is like INI on steroids. While INI files have sections and key-value pairs, TOML adds proper data types (strings, integers, floats, booleans, dates), arrays, nested tables, multi-line strings, and a formal specification. TOML is fully standardized and unambiguous, unlike INI which has many variations.
Can I convert TOML back to JSON?
Yes! Use our TOML to JSON converter tool to convert in the opposite direction. You'll find it in the Code Conversion Tools section.
Is my data secure?
Absolutely! All conversion happens entirely in your browser using JavaScript. Your JSON data never leaves your computer and is not sent to any server. You can even use this tool offline once loaded.