JSON to TOML Converter

Example: a deploy config in JSON and TOML

{
  "build": {
    "command": "npm run build",
    "publish": "dist"
  },
  "redirects": [
    {
      "from": "/blog/*",
      "to": "/news/:splat",
      "status": 301
    },
    {
      "from": "/old-pricing",
      "to": "/pricing",
      "status": 302,
      "force": true
    }
  ]
}

[build]
command = "npm run build"
publish = "dist"

[[redirects]]
from = "/blog/*"
to = "/news/:splat"
status = 301

[[redirects]]
from = "/old-pricing"
to = "/pricing"
status = 302
force = true

How JSON data types map to TOML

JSON and TOML share most value types, so most of a JSON file carries over unchanged. The differences are in structure and in one missing type: TOML has no null.

What happens to null values when converting JSON to TOML?

TOML has no null, so a key set to null cannot be written as it is. The converter removes the key and lists it under the output with its full path, such as project.license. If your program expects the key to exist, switch the null values option to write an empty string instead.

How are nested JSON objects written in TOML?

Each nested object becomes a table header with a dotted path, such as [tool.ruff]. Plain keys are written before any table, because in TOML every key after a header belongs to that header.

Does the converter keep integers and floats apart?

Yes. 30 stays an integer and 30.0 stays a float. Most converters turn both into30. Large IDs above 2⁵³ also keep every digit instead of being rounded.

What the converter changes in your output

• Top-level arrays and values are placed under a root key, because a TOML document must start as a table.
• Key order follows the TOML rule: plain keys first, then [tables], then [[arrays of tables]].
• Keys with spaces, dots or non-ASCII letters are quoted, for example "my key" = 1.
• Comments cannot come across, because strict JSON has none.

Why does a top-level JSON array need a key in TOML?

A TOML file is always a table of key and value pairs. A JSON file that starts with [ has no key to hang the list on, so the converter names it root and tells you it did.

Can I convert JSON with comments or trailing commas?

Not yet. The converter reads strict JSON, so a tsconfig.json with comments shows an error at the first comment. Remove comments and trailing commas first.

Where TOML configuration files are used

Converting JSON to TOML usually means moving settings into one of these files:

• Cargo.tomlRust package manifest
• pyproject.tomlPython packaging and tool settings
• hugo.tomlHugo site configuration
• wrangler.tomlCloudflare Workers configuration
• netlify.tomlNetlify build and redirect rules

JSON vs TOML for configuration files

Is TOML better than JSON for config files?

For files people edit by hand, usually yes: TOML allows comments, has real dates, and reads well without braces. JSON stays the better choice for data that programs send to each other.

How do I convert TOML back to JSON?

Use the TOML to JSON converter. It works the same way, in the other direction.

Is your JSON private?

Is my JSON uploaded to a server?

No. Opening a file reads it on your device. You can check this in your browser's network panel: converting makes no requests.