Input JSON

Converted TOML

What is JSON to TOML Converter?

Need to convert your JSON (JavaScript Object Notation) to TOML (Tom's Obvious, Minimal Language)? This tool does that instantly. TOML is a human-readable configuration format that's perfect for config files, while JSON is standard for APIs. Convert between them whenever you need.

According to MDN Web Docs, both JSON and TOML are popular data formats. TOML is often used in config files (like Cargo.toml for Rust, pyproject.toml for Python, or package.json alternatives), while JSON is standard for APIs. Objects map to TOML tables, a list of objects maps to an array of tables, and integers past JavaScript's 2^53 limit keep every digit. TOML has no null, so null values are left out and listed in a comment at the top.

Everything happens in your browser – your data stays private.

What Makes This Tool Different

Automatic Conversion

Paste JSON and get TOML instantly. We handle all the syntax differences – quotes, brackets, commas – everything gets converted correctly.

Structure Preservation

A nested object turns into a TOML table, and a list of objects is written as an [[array of tables]] block. Strings, numbers and booleans keep their types; a JSON string of digits stays a quoted string. Nulls are the exception: TOML can't store them, so they're left out and listed.

Validation Built-In

We validate your JSON first, so you know the conversion will work. Invalid JSON gets caught before conversion starts.

File Upload Support

Got a big file? Just upload it. Works great for converting those massive JSON configs or API responses without copy-pasting.

Download TOML

One click to download your TOML file. Drop it into your project, use it in Cargo.toml, pyproject.toml, or any TOML-based config.

Syntax Highlighting

Beautiful syntax highlighting for both JSON input and TOML output. Visual feedback helps you verify the conversion looks right.

How It Works

Paste or Upload JSON

Paste your JSON into the left editor, or click "Upload" to load a file. The JSON should be valid – objects, arrays, nested structures all work. You can also click "Sample" to see an example.

Automatic Conversion

The TOML appears on the right as you type. Tables and arrays of tables follow your JSON nesting, and a comment at the top lists any null values that had to be left out.

Download or Copy

Click "Download" to save the TOML file, or "Copy" to copy it to your clipboard. The TOML is ready to use in your config files or applications.

When You'd Actually Use This

Rust Projects

Convert JSON configs to TOML for Cargo.toml files. TOML is the standard format for Rust project configuration, and this tool makes it easy to convert JSON data into TOML format.

Python Projects

Convert JSON to TOML for pyproject.toml files. Many Python tools now use TOML for configuration, and this converter helps you migrate from JSON.

Config File Migration

Migrating from JSON configs to TOML? This tool makes it easy. Convert your existing JSON configuration files to TOML format quickly.

Tool Compatibility

Some tools require TOML format. Convert your JSON data to TOML when working with tools like Cargo, Poetry, or other TOML-based systems.

Common Questions

Is my JSON data stored?

Nope. Everything happens right in your browser. Your JSON never leaves your computer – we don't even see it.

What JSON formats work?

The converter works with any valid JSON structure – objects, arrays, nested objects, and mixed types. It analyzes the structure and converts it to equivalent TOML.

How are nested objects handled?

Each nested object is written as a TOML table ([database]), while a list of objects is written as an array of tables ([[servers]]). Strings, numbers and booleans keep their types. TOML has no null, so "key": null is left out and listed in a comment at the top; a null inside an array gives an error, and a top-level array or null gets a friendly message because TOML needs a table at the top.

Can I convert TOML back to JSON?

Yep. Use our TOML to JSON converter to convert TOML files back to JSON format.

What if my JSON has special characters?

Special characters are properly handled in TOML. Strings with quotes or other TOML syntax characters are escaped correctly.

Does it work with large datasets?

Yep. Since everything happens in your browser, it depends on your device. Small to medium JSON structures convert instantly. Really huge structures might take a few seconds.

Other JSON Tools You Might Need

Conversion is just one JSON task. Here are other tools that work well together: