What is TOML and why use it?

TOML (Tom's Obvious, Minimal Language) is a configuration file format designed to be easy to read and write. It is used in Rust projects (Cargo.toml), Python packaging (pyproject.toml), Hugo static sites (config.toml), Gitea, and many other tools. TOML has explicit types, a clear table section syntax, and avoids the ambiguity found in YAML. Converting TOML to JSON is useful when consuming configuration in systems or languages that have better JSON support than TOML support.

How are TOML tables converted to JSON?

TOML table headers like [server] create a nested JSON object. Key-value pairs under the header become properties of that object. Dotted table headers like [database.pool] create nested objects at each level. Arrays of tables defined with [[items]] become a JSON array of objects, with each [[items]] section adding one element to the array.

How are TOML datetimes handled in JSON?

TOML has four datetime types. Offset datetimes (with Z or a numeric offset like +05:30) are converted to JavaScript Date objects and serialized as ISO 8601 strings. Local datetimes and local dates without a timezone component are kept as strings in their original TOML format, since JavaScript Date cannot represent timezone-less datetimes without losing information. Local times are also kept as strings.

What happens to inf and nan values?

JSON does not support Infinity or NaN as numeric literals. The TOML parser converts these special float values to the strings inf, -inf, and nan in the JSON output. If your downstream system needs a specific representation, replace these strings manually after conversion. Common alternatives are null, 0, or a very large number like 1e308.

Can I convert large TOML files?

Yes. The parser runs entirely in your browser and has no size limit beyond what your browser's memory can handle. For typical configuration files — even large ones with thousands of entries — conversion is instantaneous. For very large generated TOML files (megabytes of data), the browser may take a moment but will still complete the conversion.

Does the tool validate TOML?

Yes, partially. The parser enforces TOML syntax rules and will report a parse error with the line number if it encounters invalid TOML. It catches duplicate keys, mismatched brackets, unterminated strings, invalid escape sequences, and invalid number literals. However, some semantic TOML rules (such as type consistency within heterogeneous arrays) are not fully validated. Use the error message to locate and fix issues in your TOML.

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Convert TOML Config Files to JSON Instantly (Cargo.toml, pyproject)

Convert TOML configuration files to JSON format instantly. Paste any TOML — Cargo.toml, pyproject.toml, config.toml — and get clean, pretty-printed JSON output. Supports all TOML types: strings (basic, literal, multi-line), integers (decimal, hex, octal, binary), floats, booleans, datetimes, arrays, inline tables, tables, and arrays of tables.

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How to Use TOML to JSON Converter

How to Use the TOML to JSON Converter

Step 1: Paste Your TOML

Paste any TOML configuration file content into the input panel. The conversion happens instantly.

Example input:

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

Output:

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

Step 2: Choose JSON Indent Style

Select from three output formats:

2 spaces — compact and widely used (default)
4 spaces — more readable for deeply nested structures
Compact — minified, no whitespace, smallest output size

Step 3: Copy or Download

Copy JSON — copies the JSON to your clipboard
Download — saves a output.json file

Supported TOML Types

TOML type	Example	JSON output
Basic string	`name = "Alice"`	`"Alice"`
Literal string	`path = 'C:\Users\'`	`"C:\\Users\\"`
Multi-line string	`""" ... """`	string with newlines
Integer	`count = 42`	`42`
Hex integer	`mask = 0xFF`	`255`
Octal integer	`perm = 0o755`	`493`
Binary integer	`flags = 0b1010`	`10`
Float	`pi = 3.14`	`3.14`
Boolean	`enabled = true`	`true`
Offset datetime	`at = 1979-05-27T07:32:00Z`	ISO string
Local date	`day = 2024-01-15`	`"2024-01-15"`
Array	`tags = ["a", "b"]`	`["a", "b"]`
Inline table	`point = {x=1, y=2}`	`{"x":1,"y":2}`
Table	`[section]`	nested object
Array of tables	`[[items]]`	array of objects

Notes on Special Values

inf, -inf, nan — converted to JSON strings since JSON does not support these numeric literals
Local datetimes and dates without timezone — output as strings in their original format
Offset datetimes — converted to ISO 8601 strings via JavaScript's Date object

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Convert TOML Config Files to JSON Instantly (Cargo.toml, pyproject)

How to Use TOML to JSON Converter

How to Use the TOML to JSON Converter

Step 1: Paste Your TOML

Step 2: Choose JSON Indent Style

Step 3: Copy or Download

Supported TOML Types

Notes on Special Values

Frequently Asked Questions

What is TOML and why use it?

How are TOML tables converted to JSON?

How are TOML datetimes handled in JSON?

What happens to inf and nan values?

Can I convert large TOML files?

Does the tool validate TOML?

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