JSON to TOML Converter – Free, Online, Private

Encoding rules

The root must be an object. Scalars are written first, then [tables] for nested objects, then [[arrays of tables]] for arrays of objects. Arrays of scalars or mixed values use inline square brackets. Strings use JSON string quoting, which is a valid TOML basic string for the characters this emits. Integers print without a decimal point. Floats print with JavaScript's default formatting. true and false are TOML booleans. Keys that are not bare identifiers are quoted.

Null and dates

TOML has no null. A JSON null throws rather than becoming a string, so you notice it. Delete the key or use an empty string before converting. Dates that are JSON strings stay strings. They are not rewritten as TOML datetimes, because a string and a datetime are different types and the page should not guess. An array of objects cannot also contain a scalar under the same key; that is illegal TOML and the converter will not emit a broken file.

Worked example

title, port and enabled are root keys. owner is a [owner] table with name inside. If tags were an array of strings it would be tags = ["math", "engines"] on one line. If tags were an array of objects, each object would be a [[tags]] table. The blank line between tables is for reading. A TOML parser does not need it. Round-tripping through the other page should return the same strings, numbers and booleans.

Use it for config, not for documents

TOML is a configuration format. A large JSON API payload with deeply mixed arrays is a poor TOML document even when the encoder succeeds. Prefer YAML or stay on JSON for those payloads. The encoder runs locally, so a config that includes a password can be reformatted without an upload.

Frequently asked questions