JSON to TOML Tutorial: Convert JSON Objects to TOML Tables

Convert a flat JSON object to TOML

{
  "name": "jsonic",
  "version": "1.0.0",
  "private": true,
  "retries": 3
}

name = "jsonic"
version = "1.0.0"
private = true
retries = 3

Convert nested objects to TOML tables

Nested JSON objects usually become TOML tables.

{
  "server": {
    "host": "localhost",
    "port": 8080
  },
  "database": {
    "poolSize": 10
  }
}

[server]
host = "localhost"
port = 8080

[database]
poolSize = 10

Convert arrays of objects to array tables

JSON arrays that contain objects map naturally to TOML array tables.

{
  "plugins": [
    { "name": "auth", "enabled": true },
    { "name": "billing", "enabled": false }
  ]
}

[[plugins]]
name = "auth"
enabled = true

[[plugins]]
name = "billing"
enabled = false

Handle JSON null before converting

TOML does not support null. Replace null fields with a real default, remove them, or choose a sentinel string that your app understands.

// JSON input that needs cleanup
{
  "theme": null,
  "enabled": true
}

// TOML-safe version
{
  "enabled": true
}

When JSON to TOML conversion works best

• The root JSON value is an object, not an array.
• Nested objects represent configuration sections.
• Arrays contain primitives or similarly shaped objects.
• The data does not need null values.
• The output will be edited by humans as config.

Common JSON to TOML mistakes

• Trying to convert arbitrary API payloads instead of config-like objects.
• Leaving null values in the input.
• Using mixed-type arrays that are hard for config consumers to interpret.
• Expecting TOML to preserve JSON object key order as business logic.