TOML to JSON Converter Online – Local TOML Parser

Convert common TOML configuration into JSON directly in your browser, with date and precision limitations clearly explained.

Runs locally
Ready to convert

Converts a conservative TOML subset: tables, arrays of tables, dotted keys, arrays, inline tables, strings, booleans, dates, and finite numbers. Multiline strings are explicitly rejected. Comments and number notation are not preserved; dates become strings. No upload.

Paste TOML or import a local .toml file (250,000 characters maximum).

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Review date strings and inferred numeric values before use.

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TOML to JSON conversion guide

How to convert TOML configuration into JSON

Paste a TOML configuration file or import it from your computer to inspect its data as indented JSON. This first version supports a conservative TOML subset and reports unsupported features instead of silently guessing. Conversion is entirely browser-local. This tool is free to use. No account or payment is required.

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What you can do here

  • TOML tables and nested keys
  • Arrays of tables
  • Inline tables and arrays
  • Safe integer validation
  • Date and time as JSON strings
  • Explicit unsupported-feature errors
  • Browser-local file import
  • JSON copy and download

How to use

  1. Paste TOML text or import a local .toml file (up to 250,000 characters).
  2. Select Convert TOML to JSON to parse the document in your browser.
  3. Review the JSON output or correct any line-specific error; multiline strings are not supported in this initial version.
  4. Copy the result or download a .json file, and review converted dates and numeric values before reuse.

TOML tables, arrays of tables and scalar values

The first version handles ordinary and nested tables, arrays of tables, dotted keys, inline tables, arrays, strings, booleans, dates and finite numbers. Unsupported syntax raises an explicit error rather than producing a partial result.

It does not implement the complete TOML language: multiline strings are rejected. Keep the original configuration when its precise TOML syntax matters.

Dates, precision and comments require review

JSON does not have TOML's date or time types. Temporal literals become JSON strings, and source comments disappear. Original number notation such as underscores or binary and hexadecimal prefixes is not retained.

Integers that cannot be represented exactly in JavaScript's safe integer range are rejected rather than rounded. Infinity and NaN are also rejected because standard JSON cannot represent them.

Private browser-local TOML conversion

The document is parsed entirely on your device. VetaTool does not upload file contents or generated JSON, and the conversion does not execute any code or read referenced files.

Use the dedicated YAML to JSON and JSON formatter tools when you are starting with other formats. This tool does not currently convert JSON or YAML back into TOML.

Convert a nested TOML configuration

A TOML table and array become a nested JSON object and JSON array; TOML date notation is converted to a string.

TOML input

title = "VetaTool"
[server]
port = 8080
features = ["json", "yaml"]

JSON output

{"title":"VetaTool","server":{"port":8080,"features":["json","yaml"]}}

Common questions

Frequently asked questions

Does TOML to JSON upload my configuration?

No. Parsing and serialization happen locally in the browser, without uploading TOML data.

Does it support all TOML syntax?

No. This MVP supports common tables, arrays and scalar values but explicitly rejects multiline strings and any other unsupported syntax.

How are TOML dates represented?

TOML date/time literals become JSON strings. Review date types and timezone assumptions in your target application.

Will comments or exact number formatting survive?

No. JSON does not preserve TOML comments or original numeric notation, and unsafe large integers are rejected to prevent rounding.

Does it support JSON or YAML to TOML?

Not in this version. It converts TOML to JSON only; unsupported reverse conversions have not been added.

Recommended next steps

YAML to JSON Converter OnlineConvert YAML data into JSON when your configuration is in YAML format.JSON Formatter OnlineFormat and explore the generated JSON output.JSON to YAML Converter OnlineGenerate YAML from JSON when that is the required target format.

Debugging a specific YAML issue? Browse YAML troubleshooting.