JSON to TOML Converter
Paste JSON on the left, get TOML on the right. Perfect for generating Cargo.toml (Rust), pyproject.toml (Python), or any TOML-based configuration from structured data.
How to use this tool
Paste a JSON object into the input on the left. The top-level value must be an object (TOML is a table-based format).
TOML appears on the right as you type. Nested objects become [tables]; arrays of objects become [[arrays of tables]].
Copy the result into your .toml file. Scalar types (strings, integers, booleans, floats, ISO dates) map naturally.
TOML (Tom's Obvious, Minimal Language) is favored by the Rust ecosystem and increasingly by Python tooling because it is more explicit than YAML and more readable than JSON for configs. Converting from JSON lets you migrate existing config data into TOML tooling.
All conversion happens locally; nothing is uploaded.
Frequently asked questions
Why must the top-level JSON be an object?
TOML is fundamentally a key/value table format — there is no concept of a top-level array or scalar. Wrap arrays/scalars inside an object key to convert them.
How are dates handled?
ISO 8601 strings that look like dates are emitted as TOML datetimes. Other strings stay strings.
What about arrays of tables?
Arrays whose elements are all objects become TOML arrays of tables ([[name]]) which is the idiomatic way to express lists of records.
Is the conversion done locally?
Yes — using @iarna/toml, fully in your browser. No server roundtrip.