TOML Validator

Check whether TOML is syntactically valid before committing config changes.

  • Runs entirely in your browser
  • No data stored or sent to a server
  • Free forever — no signup
  • Instant conversion

Input and Output

Use the interactive encoder and decoder on this page to process your text.

Learn more about TOML

How to Validate TOML Syntax

TOML Validation

When to Validate TOML

Validate TOML before deploying configs, publishing crates, or pushing pyproject.toml changes. Catch syntax errors and invalid table definitions early instead of at build time when Cargo, pip, or other tools reject the file.

Common TOML Errors

  • Duplicate keys in the same table
  • Invalid date or datetime literals
  • Mismatched quotes in string values
  • Table headers referencing undefined parent tables

Developer Tips

  • Validate in CI before deploy: parse step on config files
  • Format after fixing errors for readable error context
  • Quote strings with special characters to avoid parse ambiguity

Frequently asked questions

Does validation check schema or just syntax?

This tool checks TOML syntax only. It does not validate against Cargo, PEP 621, or other domain schemas.

Are inline tables supported?

Yes. Inline tables and array-of-tables syntax are validated as part of standard TOML parsing.