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TOML Validator & Formatter — Free Online Tool

Validate TOML files instantly with clear error messages and line numbers. Auto-format, prettify, and convert TOML to JSON. Supports the full TOML v1.0 spec including datetimes, inline tables, and arrays of tables.

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○ Paste TOML or drag a .toml file to begin
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<\!-- Left pane: Input -->
TOML Input
0 chars 0 lines Drag & drop .toml supported
<\!-- Right pane: Output -->
Formatted TOML
0 chars 0 lines
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Frequently Asked Questions

TOML (Tom's Obvious Minimal Language) is a minimal configuration file format designed to be easy to read and write. It uses a clear key = value syntax, supports sections with [table] headers, arrays of tables with [[array]], and native types including strings, integers, floats, booleans, datetimes, arrays, and inline tables.

This validator fully supports TOML v1.0, the current stable specification, via the smol-toml library. It handles all TOML v1.0 features including RFC 3339 datetimes, multi-line strings, inline tables, arrays of tables, and hex/octal/binary integer literals.

TOML is simpler than YAML with unambiguous parsing rules and explicit section syntax. Unlike JSON, TOML supports comments and native datetime types. TOML is ideal for configuration files where readability and simplicity matter. YAML is more expressive for complex data but harder to parse correctly. JSON is best for machine-to-machine data interchange.

Yes. TOML natively supports comments using the # character. This validator fully handles TOML comments and will not produce errors for them. However, when you format or convert to JSON, comments are removed because they are not part of the parsed data structure.

No. All validation, formatting, and conversion happens entirely in your browser using the smol-toml library. Your TOML data never leaves your device and is not stored or logged anywhere.

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