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TOML Validator

Validates TOML 1.0 syntax · Line-precise errors · Lints Cargo.toml and more · No install required

Runs 100% in your browser — your schema never leaves your device
config.toml
result TOML

The share link contains your schema — share it only where you'd share the schema itself.

About the TOML validator

TOML (Tom's Obvious, Minimal Language) is a configuration format designed to be easy to read and unambiguous to parse. It's the format behind Rust's Cargo.toml, Python's pyproject.toml, and many other tools' settings. This validator and linter checks that your TOML conforms to the TOML 1.0 specification and reports any error with a precise line and column.

Because TOML is strict about types and structure, the common failures are clear: an unterminated string, a value missing after =, a duplicate key, an invalid date or number literal, or a malformed table header. The parser reports the exact line where it stopped, so a quick paste tells you what to fix.

You can use it as a Cargo.toml linter — paste the file straight in. This checks TOML syntax, not your config against a tool's expected schema. If you're weighing config formats, the YAML Validator covers the indentation-based alternative. Everything runs in your browser and nothing is uploaded.

TOML validation FAQ

Is TOML 1.0 supported?

Yes. The validator parses against the TOML 1.0 specification — the current stable version — including tables, arrays of tables, inline tables, typed values, and the full set of string and date-time literals.

What are the most common TOML errors?

An unterminated string, a missing value after =, a duplicate key, an invalid number or date literal, and a malformed [table] or [[array.of.tables]] header. Each is reported with the exact line and column where parsing failed.

Can I use it as a Cargo.toml linter?

Yes. Paste your Cargo.toml (or pyproject.toml, or any TOML config) and it will report syntax errors with line and column. It checks TOML syntax — it doesn't validate the file against Cargo's expected fields.

Should I use TOML or YAML?

TOML is explicit and bracket-delimited; YAML is more compact and expressive for deeply nested data. For a full comparison of when to choose each, see the guide YAML vs TOML at /guides/yaml-vs-toml/.