What is TOML Validator?
TOML (Tom's Obvious Minimal Language) is a configuration file format designed to be easy to read and write. It's used by Rust's Cargo, Python's pip, and many other tools. This validator checks your TOML files for syntax errors like unclosed strings, duplicate keys, and invalid values.
How to Use
- Paste your TOML content in the text area
- Click Validate to check for syntax errors
- Review any errors with line numbers
- Fix errors and re-validate
Why Use This Tool?
Tips & Best Practices
- TOML section headers use [section] syntax
- Strings must be wrapped in double or single quotes
- Booleans are lowercase: true or false
- Comments start with #
- Use [[array]] for arrays of tables
Frequently Asked Questions
What is TOML?
TOML (Tom's Obvious Minimal Language) is a configuration file format designed to map unambiguously to a hash table. It's used by Rust's Cargo (Cargo.toml), Python's pip and build tools (pyproject.toml), and many other projects. It aims to be more readable than JSON for configuration while being simpler than YAML.
TOML vs YAML vs JSON for config files?
TOML is best for simple, flat configuration with clear types. YAML is more powerful but has complex behavior (anchors, references, multiple document types). JSON is universal but lacks comments and is harder to write by hand. Choose TOML for straightforward configs, YAML for complex structures, and JSON for API/data exchange.
What files use TOML format?
Common TOML files include Cargo.toml (Rust), pyproject.toml (Python), Buf.gen.yaml alternative configs, Hugo config.toml, and many modern CLI tools. The .toml extension is standard.
Does this validator support all TOML features?
This validator covers the most common TOML features: sections, key-value pairs, strings, integers, floats, booleans, arrays, and inline tables. Some advanced features like multiline strings, dotted keys, and datetime values have limited support.
How is TOML different from INI files?
TOML is inspired by INI files but is a strict specification with proper type support. INI files have no standard format — different parsers handle types, nesting, and arrays differently. TOML has a formal specification (toml.io) that all compliant parsers must follow.
Can I convert TOML to JSON?
Yes! TOML maps directly to a JSON object. Sections become nested objects, and TOML types map to JSON types. Use our YAML to JSON converter for similar conversions, or check back for a dedicated TOML to JSON tool.