Convert TOML to JSON and back, live in your browser. Full support for dates, arrays of tables, and large integers with a spec-compliant parser. Two-way and 100% client-side.
TOML has become the configuration format of choice for modern tooling — Rust's Cargo, Python's Poetry and pyproject.toml, and many other tools rely on it because it is clean and hard to get wrong. But when you need to feed that config into a script, an API, or a system that speaks JSON, you need a reliable converter. This tool does exactly that, live and entirely in your browser.
It is built on a fully spec-compliant TOML 1.0 parser, so it correctly handles the features simpler converters trip over: dates and timestamps, inline tables, arrays of tables, multi-line strings, and large integers. Paste your TOML on the left and see clean, formatted JSON appear instantly on the right, with clear inline errors if the input has a syntax problem.
Two-Way Conversion, Formatting & File Support
Unlike most free converters that only go one way, this tool is fully bidirectional: switch to JSON → TOML with a single click to turn a JSON object back into a clean TOML config. It sensibly handles the structural differences between the two formats — for example, dropping JSON null values, which TOML does not support, and requiring an object at the top level.
You can control the JSON output with 2-space, 4-space, tab, or minified formatting, upload a file directly instead of pasting, and copy or download the result in one click. Everything runs client-side, so it is fast and completely private — ideal for converting configuration that may contain sensitive values.
How to use this TOML to JSON Converter?
1
Paste TOML
Drop your TOML config into the input panel, or upload a .toml file.
2
Get JSON
Formatted JSON appears instantly, with dates and large numbers handled correctly.
3
Pick Format
Choose 2-space, 4-space, tab, or minified output.
4
Swap or Export
Click swap to convert JSON back to TOML, then copy or download the result.
Frequently Asked Questions
TOML (Tom's Obvious, Minimal Language) is a configuration file format designed to be easy to read and write. It powers config files like Rust's Cargo.toml and Python's pyproject.toml, and is a popular, less error-prone alternative to YAML.
Yes. This is a two-way converter: click the swap button to switch between TOML → JSON and JSON → TOML. Note that because TOML has no top-level arrays or null values, JSON must be an object, and null values are dropped during conversion to TOML.
TOML dates and timestamps are converted to standard ISO 8601 strings in the JSON output. Very large integers that exceed JavaScript's safe number range are handled without losing precision or crashing — something many free converters get wrong.
No. All parsing and conversion happen entirely in your browser using a spec-compliant TOML engine. Your configuration data never leaves your device, so it is safe for private or secret-bearing files.
The most common cause is a syntax error in the source — a missing quote, an unclosed bracket, or an invalid date. The tool shows the exact line and reason. For JSON → TOML, remember the top level must be an object, not an array or a bare value.