Developer Tools

TOML Formatter

Paste TOML configuration and validate its syntax instantly. Catches common errors like duplicate keys, invalid values, and malformed tables, with exact line numbers reported.

Runs in your browser No data sent to servers Copy or download result
toml TOML
Runs in your browser; code never leaves your device
Input Text Output Text Browser-only No upload by default

Features

  • Validates TOML syntax with precise error locations
  • Identifies duplicate key errors
  • Checks table and array-of-tables structure
  • Formats TOML with consistent spacing
  • Browser-only. No upload

How to use it

  1. Paste your TOML content into the input panel.
  2. Validation runs automatically.
  3. If valid, formatted TOML appears in the output.
  4. If invalid, the error message shows the line and nature of the problem.

Use cases

  • Validating Cargo.toml for Rust projects
  • Checking Hugo or Zola config.toml files
  • Debugging Pyproject.toml configuration
  • Verifying CI/CD pipeline TOML config

Limitations

  • The formatter spaces key/value pairs and separates section headers.
  • Very large input can be slower on older devices.
  • This utility is designed for common snippets and local inspection, not as a full security or language-specific validator.
See also

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Questions & answers

Frequently asked

What version of TOML is supported?

TOML v1.0 specification is used, including inline tables, arrays of tables, and all scalar types.

Does TOML Formatter upload my input?

Your file or text is processed in your browser and is not uploaded.

What does TOML Formatter output?

It outputs cleaner TOML text. The formatter spaces key/value pairs and separates section headers.

Should I review TOML Formatter output before using it?

Yes. Developer formats and snippets can be context-sensitive, so review generated output before using it in production.