Free JSON to TOML — tables · [[arrays]] · inline values
Convert JSON to TOML
Tables, array of tables
and all TOML types.
Convert any JSON object to valid TOML.
Nested objects become tables, arrays of objects become
[[sections]].
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Nested objects → [tables]
Arrays of objects → [[sections]]
Always free
JSON to TOML Converter
100% client-side
TOML requires all keys at the root level to be either scalars or tables.
Arrays of primitive values become inline TOML arrays.
Arrays of objects become
[[array of tables]].
JSON input
TOML ready
JSON to TOML conversion rules
How JSON types and structures map to TOML equivalents.
| JSON | TOML output | Notes |
|---|---|---|
{"key": "value"} | key = "value" | Root-level strings |
{"a": {"b": 1}} | [a] | Nested objects → tables |
{"a": {"b": {"c": 1}}} | [a.b] | Deep nesting → dotted headers |
{"arr": [1, 2, 3]} | arr = [1, 2, 3] | Scalar arrays → inline |
{"bins": [{...}, {...}]} | [[bins]] | Object arrays → array of tables |
true / false | true / false | Direct mapping |
42 / 3.14 | 42 / 3.14 | Numbers without quotes |
null | "" | TOML has no null — becomes empty string |
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JSON serialized to valid
TOML. No upload needed.
The TOML serializer correctly handles the ordering constraint of TOML: scalar keys must come before table keys in the same section. Arrays of objects are emitted as [[section]] entries, and intermediate empty table headers are suppressed.
Correct key ordering
Scalars always before tables in each section — the ordering required by the TOML spec.
No empty sections
Intermediate table headers with no direct keys are suppressed — [a] is omitted when only [a.b] has content.
[[Array of tables]]
Arrays of objects become [[section]] entries — the idiomatic TOML pattern for repeated configuration blocks.
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Frequently asked questions
How are nested JSON objects converted to TOML?
Nested objects become TOML table headers. {profile: {release: {opt-level: 3}}} becomes [profile.release] with opt-level = 3 underneath. Intermediate sections with no direct scalar keys are omitted to keep the output clean.
How are JSON arrays converted to TOML?
Arrays of scalars (strings, numbers, booleans) become TOML inline arrays: tags = ["admin", "user"]. Arrays of objects become [[array of tables]] entries — each object in the array gets its own [[section]] header with the object's keys below it.
How do I convert JSON to TOML in Python?
pip install tomli-w. Then: import tomli_w, json; data = json.loads(json_str); print(tomli_w.dumps(data)). Note: tomli_w requires all dict keys to be strings and does not support null values — convert nulls to empty strings before encoding.
Is the JSON to TOML converter free?
Yes, completely free. No file size limits, no account required.