JSON to TOML Converter

How to convert JSON to TOML

1. Paste a JSON object or open a file. The TOML appears as you type.
2. Check the note under the output: it says when values were left out.
3. Press ⇄ to check the round trip in TOML to JSON.

Invalid JSON shows its line and column; the JSON validator explains the message.

Example: a Hugo site config

{
  "baseURL": "https://example.org/",
  "title": "Field Notes",
  "draft": null,
  "params": { "author": "R. Okafor", "showToc": true, "ratio": 1.0 },
  "menu": {
    "main": [
      { "name": "Posts", "url": "/posts/", "weight": 1 },
      { "name": "About", "url": "/about/", "weight": 2 }
    ]
  }
}

baseURL = "https://example.org/"
title = "Field Notes"

[params]
author = "R. Okafor"
showToc = true
ratio = 1

[[menu.main]]
name = "Posts"
url = "/posts/"
weight = 1

[[menu.main]]
name = "About"
url = "/about/"
weight = 2

The note TOML has no null. 1 null value was left out. refers to draft.

How JSON maps to TOML

• Plain values come first, then each nested object becomes a table named by its path, such as [params] or [server.http].
• Arrays of objects become arrays of tables: one [[menu.main]] block per item.
• Arrays of plain values stay inline: regions = [ "eu-north-1", "eu-west-1" ].
• Keys with spaces or dots are quoted ("dotted.key" = 2) so they are not read as nested tables.
• null has no TOML form, so the key is left out and counted in the note.
• Whole numbers become integers: 1.0 became ratio = 1. Add the .0 back if the reader wants a float.

The top level must be an object

A JSON array or a single value cannot be a TOML document. The tool answers TOML needs an object at the top level. and, for an array, suggests wrapping it: {"items": [...]} gives one [[items]] block per item.

For Kubernetes or Docker Compose files, use JSON to YAML instead.