TOML Validator

Paste or type TOML to instantly validate and parse it. Errors show exact line and column numbers.

Common TOML Mistakes

  • × Duplicate keys — each key must be unique within a table.
  • × Mixed array types — all elements in an array must be the same type.
  • × Missing quotes on strings — bare values like hello world are invalid; use "hello world".
  • × Redefining a table — you can't define [section] more than once.

TOML Quick Reference

  • · Tables — [section] starts a new table.
  • · Array of tables — [[items]] creates an array of table objects.
  • · Multiline strings — use triple quotes """...""".
  • · Dates — ISO 8601 format is natively supported: 2024-01-15T10:30:00Z.

Frequently Asked Questions

What is TOML?

TOML (Tom's Obvious, Minimal Language) is a configuration file format designed to be easy to read. It's used by Rust's Cargo.toml, Python's pyproject.toml, Hugo, and many other tools.

Why does the output show JSON?

The parsed TOML is displayed as JSON so you can see exactly how the data was interpreted — types, nested tables, arrays of tables, and date values all become visible.

What's the difference between [table] and [[table]]?

[table] defines a single object. [[table]] (double brackets) defines an element in an array of objects — each occurrence appends a new entry to the array.

Is my data sent anywhere?

No — all validation and parsing happens entirely in your browser. Nothing is sent to any server.