Convert TOML to JSON

Reading TOML as JSON

TOML files are easy for people to edit, but many tools, dashboards and scripts only understand JSON. Converting a Cargo.toml, pyproject.toml, netlify.toml or Hugo config to JSON lets you inspect it with JSON tools, validate it or load it without a TOML parser.

This converter uses smol-toml, a TOML 1.0 compliant parser. Tables become objects, array tables become arrays of objects and inline tables become nested objects. Invalid TOML produces an error message rather than partial output.

TOML vs JSON at a glance

How to convert TOML to JSON

1. 1

   Step 1: Select the .toml file

   Drop your config file onto the converter.

2. 2

   Step 2: Keep JSON as the target

   JSON is preselected. YAML and XML are also available.

3. 3

   Step 3: Convert

   The TOML is parsed and written as indented JSON.

4. 4

   Step 4: Download

   Save the .json file and use it anywhere.

Type mapping

Why convert TOML to JSON

• Inspecting project metadata. Read package names, versions and dependencies in JSON tools.

• CI scripts. Parse config values in environments that ship only a JSON parser.

• Validation. Check configs against a JSON Schema.

• Migrating tools. Move settings to a JSON-based configuration system.

Precision and special values

JSON numbers are handled as double precision floats by most software, so integers larger than about nine quadrillion (2 to the 53rd power) cannot be represented exactly. Rather than silently changing such a value, the converter stops with an error; write very large numbers as quoted strings in the TOML if you need them.

TOML allows inf and nan as float values; JSON has no equivalent, and they are written as null. Comments are removed because JSON cannot hold them.

When conversion fails

TOML is strict. Defining the same key twice, redefining a table, or mixing a table with a dotted key of the same name is an error, and the converter reports it. The message usually includes the line where the problem was found.

Fixing the TOML in an editor with syntax highlighting is the quickest way to resolve these errors.

• Duplicate keys: not allowed.
• Unquoted strings: not allowed.
• Trailing commas in inline tables: not allowed.

Tips for TOML to JSON

• Quote every string value in TOML; bare words are errors.
• Keep dates unquoted in TOML if you want them treated as dates.
• Use JSON to TOML to convert edited data back.
• For large dependency lists, pipe the JSON into jq for quick queries.

TOML to JSON questions