API reference

Convert TOML to JSON

Convert a TOML 1.0 document to JSON, with line and column for any error.

GET POST /api/convert/toml-to-json MCP tool toml_to_json

Parses input as TOML 1.0.0 and returns the same data as JSON text and as a JSON value. Tables become objects and keep their order. Integers within ±(2^53 − 1) are numbers; larger ones are decimal strings so no digit is lost. inf, -inf and nan become the strings "inf", "-inf" and "nan". An offset date-time becomes an ISO 8601 string with its offset (1979-05-27T07:32:00.000-08:00); a local date-time, date or time becomes its TOML text (1979-05-27T07:32:00.000, 1979-05-27, 07:32:00.000). Fractional seconds are written to the millisecond. Comments are dropped: JSON has none.

Browser version (runs locally): TOML Format & Validate.

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POST /api/convert/toml-to-json with a JSON body

Parameters

Parameter Type Default Description
input required string (≤ 200000 chars) — The TOML text, as a string field or a raw text/plain POST body.
indent integer (0–8) 2 Spaces per JSON indentation level; 0 gives minified JSON.

Also accepted on every endpoint: format (json | text). Parameters may come from the query string, a JSON object body, an urlencoded or multipart form, or (for input) a text/plain body.

Global parameters
Parameter Type Default Description
format json | text json json returns the documented object. text returns only the primary value as text/plain (see "Text output").

Response 200 application/json

Field Type Description
json string The JSON text.
value any The same data as a JSON value.

Text output (format=text, text/plain): The JSON text.

Errors

Errors are JSON: {"error": "<message>", "code": "<code>", "param": "<name>"?}.

Status Code When
422 unprocessable_input The TOML is invalid (syntax error, duplicate key or table, integer beyond 64 bits); the message gives the line and column.
400 invalid_parameter input is longer than 200,000 characters, or indent is outside 0–8.
400 missing_parameter A required parameter is absent.
400 unknown_parameter A parameter name is not in the table above (typos are rejected, not ignored).
413 payload_too_large The request body exceeds 1 MiB.
405 method_not_allowed A method other than GET, POST or OPTIONS.

Behaviour

  • Idempotent: the same arguments always return the same result.
  • Requires a client ID and secret (authentication). Each call is recorded as one metadata row against your client ID; inputs and outputs are never stored or logged. Responses carry cache-control: no-store.
  • CORS: any origin may call this endpoint from a browser, using your credentials.

Examples

Responses below were produced by running each request through this code at build time. Long strings are shortened.

Tables, an array of tables and dates

curl -X POST 'https://util.caruana.me/api/convert/toml-to-json' \
  -H 'content-type: application/json' \
  -d '{"input":"title = \"TOML Example\"\n\n[owner]\nname = \"Tom\"\ndob = 1979-05-27T07:32:00-08:00\n\n[[products]]\nname = \"Hammer\"\nsku = 738594937\n\n[[products]]\nname = \"Nail\"\nsku = 284758393\ncolor = \"gray\"\n"}'

Response 200

{
  "json": "{\n  \"title\": \"TOML Example\",\n  \"owner\": {\n    \"name\": \"Tom\",\n    \"dob\": \"1979-05-27T07:32:00.000-08:00\"\n  },\n  \"products… (150 more characters)",
  "value": {
    "title": "TOML Example",
    "owner": {
      "name": "Tom",
      "dob": "1979-05-27T07:32:00.000-08:00"
    },
    "products": [
      {
        "name": "Hammer",
        "sku": 738594937
      },
      {
        "name": "Nail",
        "sku": 284758393,
        "color": "gray"
      }
    ]
  }
}
Same call as an MCP tools/call
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "toml_to_json",
    "arguments": {
      "input": "title = \"TOML Example\"\n\n[owner]\nname = \"Tom\"\ndob = 1979-05-27T07:32:00-08:00\n\n[[products]]\nname = \"Hammer\"\nsku = 738594937\n\n[[products]]\nname = \"Nail\"\nsku = 284758393\ncolor = \"gray\"\n"
    }
  }
}

Special floats and a 64-bit integer, minified

curl -X POST 'https://util.caruana.me/api/convert/toml-to-json' \
  -H 'content-type: application/json' \
  -d '{"input":"big = 9223372036854775807\nratio = inf\nmissing = nan\nwhen = 07:32:00\n","indent":0}'

Response 200

{
  "json": "{\"big\":\"9223372036854775807\",\"ratio\":\"inf\",\"missing\":\"nan\",\"when\":\"07:32:00.000\"}",
  "value": {
    "big": "9223372036854775807",
    "ratio": "inf",
    "missing": "nan",
    "when": "07:32:00.000"
  }
}
Same call as an MCP tools/call
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "toml_to_json",
    "arguments": {
      "input": "big = 9223372036854775807\nratio = inf\nmissing = nan\nwhen = 07:32:00\n",
      "indent": 0
    }
  }
}