TOML to JSON Converter

Whether you are debugging a Cargo.toml, reading a pyproject.toml in JavaScript or feeding configuration to a tool that only understands JSON, converting TOML to JSON shows exactly how the file is interpreted. The converter implements the full TOML 1.0 specification.

1. Paste TOML or drop a .toml file.
2. Syntax errors are reported with the parser's message.
3. Choose the JSON indentation in Options.
4. Copy or download the JSON.

Example

[package]
name = "dataswitch"
version = "0.4.1"
edition = "2021"

[dependencies]
serde = { version = "1.0", features = ["derive"] }
tokio = "1"

[[bin]]
name = "dsp"
path = "src/main.rs"

{
  "package": {
    "name": "dataswitch",
    "version": "0.4.1",
    "edition": "2021"
  },
  "dependencies": {
    "serde": {
      "version": "1.0",
      "features": [
        "derive"
      ]
    },
    "tokio": "1"
  },
  "bin": [
    {
      "name": "dsp",
      "path": "src/main.rs"
    }
  ]
}

Inline tables such as the serde entry become nested objects, and [[bin]] becomes an array — even with a single entry, because arrays of tables are always arrays.

Supported TOML features

• Tables, dotted keys, nested and inline tables.
• Arrays and arrays of tables ([[…]]).
• Basic, literal and multi-line strings.
• Integers (including hexadecimal, octal and binary), floats, booleans.
• Offset date-times, local date-times, dates and times — written to JSON as ISO 8601 strings.

Common TOML mistakes

• Defining the same key or table twice.
• Unquoted strings: name = my-app must be name = "my-app".
• Line breaks inside inline tables, which TOML 1.0 does not allow.
• Mixing a key and a table with the same name.

Why convert TOML to JSON?

JSON is supported everywhere: JavaScript can read it natively, jq can query it, and JSON Schema can validate it. Converting a configuration file is also a reliable way to verify its structure before committing it.

Real-world examples

Read Cargo.toml or pyproject.toml in a script

Tools written in JavaScript or shell (with jq) handle JSON more easily than TOML. Convert once to see the exact paths to the values you need.

[package]
name = "csv-tool"
version = "1.0.0"

[dependencies]
serde = { version = "1.0", features = ["derive"] }

{
  "package": {
    "name": "csv-tool",
    "version": "1.0.0"
  },
  "dependencies": {
    "serde": {
      "version": "1.0",
      "features": [
        "derive"
      ]
    }
  }
}

Check a Netlify or Hugo config

Arrays of tables ([[redirects]]) are easy to get wrong. The JSON shows each one as an element of an array.

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

[[redirects]]
from = "/old"
to = "/new"
status = 301

{
  "build": {
    "command": "npm run build",
    "publish": "dist"
  },
  "redirects": [
    {
      "from": "/old",
      "to": "/new",
      "status": 301
    }
  ]
}

Common errors and how to fix them

Related guides

• JSON Lines (JSONL) explained

Convert TOML to JSON in code

For one-off files the tool above is quickest. To automate the same task in a script or pipeline, these snippets are a good starting point.

Python 3.11+ (tomllib)

import json
import tomllib  # built into Python 3.11+

with open("Cargo.toml", "rb") as f:
    data = tomllib.load(f)

print(json.dumps(data, indent=2, default=str))

Node.js (smol-toml)

import { parse } from "smol-toml";  // npm install smol-toml
const json = JSON.stringify(parse(text), null, 2);

Frequently asked questions

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