How are nested JSON objects converted to TOML?

Each nested object becomes a TOML table section. The section header uses the full dot-separated path of the object. For example, a JSON object at database.pool becomes [database.pool] in TOML. Within each section, all primitive key-value pairs appear first, followed by any deeper sub-tables. This order is required by the TOML specification.

How are JSON arrays converted?

Arrays of primitive values (strings, numbers, booleans, nulls) are output as inline TOML arrays on a single line, for example tags = ["alpha", "beta"]. Arrays where every element is an object are output as TOML array-of-tables using [[double-bracket]] headers — one header per element. If an array mixes objects and primitives, it is serialized as a JSON-encoded string value with a comment marking it for manual review.

What happens to null values?

TOML has no null type. JSON null values are converted to the string "null" in the TOML output, with an inline comment noting that the original value was null and that the type should be updated. If you need a different representation (empty string, 0, a missing key), adjust the output manually after conversion.

What does the ISO 8601 datetime detection option do?

When enabled, string values that match ISO 8601 date or datetime patterns are output as native TOML datetime values without surrounding quotes. The supported formats are: offset datetimes like 1979-05-27T07:32:00Z or 1979-05-27T07:32:00+05:30, local datetimes like 1979-05-27T07:32:00, local dates like 2024-01-15, and local times like 07:32:00. Disable this option if your data contains date-formatted strings that should remain as plain text.

Can I use this to generate a Cargo.toml or pyproject.toml?

Yes, partially. The tool correctly generates the TOML structure — tables, array-of-tables, inline arrays, and primitive values. However, some TOML files like Cargo.toml have conventions beyond syntax (such as the [dependencies] table using inline tables for features). The output is valid TOML and structurally correct, but you may need to manually adjust specific sections to match the expected format of the target tool.

Does the output follow the TOML specification order?

Yes. The generator always places all primitive key-value pairs in a section before any sub-table headers. This is required by the TOML v1.0 specification — a key-value pair cannot appear after a table header that belongs to the same implicit table. The generator also separates sections with blank lines for readability.

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Convert JSON to TOML Config Format Instantly (Tables & Arrays)

Convert JSON objects to TOML configuration file format instantly. Nested objects become [table] sections, arrays of objects become [[array-of-tables]], and primitive arrays output as inline arrays. Optionally auto-detects ISO 8601 date strings and converts them to native TOML datetime values. Outputs clean, human-readable TOML ready for Cargo.toml, pyproject.toml, or any TOML-based config.

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How to Use JSON to TOML Converter

How to Use the JSON to TOML Converter

Step 1: Paste Your JSON

Paste any JSON object into the input panel. The TOML is generated instantly.

Example input:

{
  "server": {
    "host": "localhost",
    "port": 8080,
    "debug": false
  }
}

Output:

[server]
host = "localhost"
port = 8080
debug = false

Step 2: Configure Options

Convert ISO 8601 strings to TOML datetime values — when enabled, string values that match ISO 8601 date/datetime formats are output as native TOML datetime values (without quotes) instead of quoted strings.

For example, "2024-01-15T10:00:00Z" becomes 2024-01-15T10:00:00Z in TOML.

Disable this option if you have date-like strings that should remain as plain strings.

Step 3: Understand the Output Structure

The generator follows TOML conventions:

Primitive values (string, number, boolean, null) → key = value pairs
Nested objects → [table.section] headers
Arrays of all-objects → [[array-of-tables]] headers (one per element)
Arrays of primitives → inline arrays [1, 2, 3]
null values → "null" string with an inline comment

All primitives in a section appear before any sub-table sections, as required by the TOML specification.

Step 4: Copy or Download

Copy TOML — copies to clipboard
Download — saves an output.toml file

Type Mapping Reference

JSON type	Example	TOML output
String	`"hello"`	`"hello"`
Multi-line string	`"line1\nline2"`	`""" ... """`
Integer	`42`	`42`
Float	`3.14`	`3.14`
Boolean	`true`	`true`
null	`null`	`"null"` + comment
String (ISO date)	`"2024-01-15"`	`2024-01-15` (with option)
Array of primitives	`[1,2,3]`	`[1, 2, 3]`
Array of objects	`[{...}, {...}]`	`[[key]]` sections
Nested object	`{"key": {...}}`	`[key]` section

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Convert JSON to TOML Config Format Instantly (Tables & Arrays)

How to Use JSON to TOML Converter

How to Use the JSON to TOML Converter

Step 1: Paste Your JSON

Step 2: Configure Options

Step 3: Understand the Output Structure

Step 4: Copy or Download

Type Mapping Reference

Frequently Asked Questions

How are nested JSON objects converted to TOML?

How are JSON arrays converted?

What happens to null values?

What does the ISO 8601 datetime detection option do?

Can I use this to generate a Cargo.toml or pyproject.toml?

Does the output follow the TOML specification order?

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