JSON to TOML
ConverterConvert JSON to TOML config format with nested tables, arrays and typed values for Rust, Python and other project configuration and manifest file generation.
Related Tools
About JSON to TOML
TOML (Tom's Obvious Minimal Language) is praised for its clear, unambiguous semantics and serves as the standard config format for modern toolchains like Rust's Cargo and Python's pyproject.toml. This tool converts JSON to TOML locally in your browser, correctly turning objects into tables, arrays of objects into arrays of tables ([[table]]), and scalar values with their types intact. Two boundaries are worth knowing up front: TOML has no null type, so keys with null values are dropped, and readability declines with very deep nesting, so consider splitting configs beyond three or four levels. Key insertion order is preserved to make item-by-item comparison easy, and unsupported constructs trigger a readable notice rather than failing silently. Because conversion happens entirely on-device, nothing is uploaded — safe for configs holding secrets or environment-specific values. Handy when migrating legacy JSON configs to TOML and when rewriting API sample JSON into maintainable declarative config for review in your repository.
How to Use
- Open the JSON to TOML tool
- Select the source and target formats
- Adjust the output options as needed
- Click the Convert button; results appear in real time
- Copy or export the result
Use Cases
- Generate Cargo config — Turn a JSON dependency list into the [dependencies] section of Cargo.toml.
- Migrate Python projects — Convert JSON-style metadata from setup.py into the TOML structure pyproject.toml needs.
- Unify config format — When a team standardizes on TOML, batch-convert legacy JSON configs.
- Understand TOML tables — Use JSON↔TOML side by side to grasp nested tables and arrays of tables.
- Toolchain integration — Convert API JSON to TOML for tools like Hugo or Netlify to read.
- Config templating — Convert a JSON template from a config generator into TOML for a project that uses pyproject.toml.
- Cross-language sharing — Export a JSON schema as TOML so a Rust and Python project share the same config structure.
FAQ
How is JSON null converted?
TOML has no null type. Keys with null values are skipped because TOML cannot represent emptiness — note these keys disappear after conversion.
What do nested object arrays become?
Arrays of objects become TOML's "array of tables" syntax [[table]], the standard way TOML expresses repeated structures.
Is deep nesting supported?
Yes, but TOML readability suffers with very deep nesting. Beyond 3-4 levels, consider splitting the config.
How are date-times handled?
Dates in JSON are usually strings and stay strings in TOML. TOML's native date types require RFC 3339 format to be recognized.
Is key order preserved?
Yes, insertion order is kept, so you can compare the original JSON and the result segment by segment to confirm nothing slipped.
Can I convert back?
Use our TOML to JSON tool for the reverse direction.