TOML ↔ JSON Converter — Free Online Tool
Convert between TOML and JSON formats with automatic direction detection. Useful for working with Rust Cargo.toml files, Python pyproject.toml, Hugo config files, and any TOML-based configuration. Uses smol-toml for spec-compliant TOML 1.0 parsing.
100% client-side. No uploads. Your data never leaves your browser.
How to use TOML ↔ JSON Converter
- Paste TOML or JSON into the input.
- The tool auto-detects the direction.
- Click the mode toggle to override if needed.
- Copy or download the output.
Frequently Asked Questions
What TOML version is supported?
smol-toml implements TOML 1.0, the current stable specification.
Can all JSON convert to TOML?
Most JSON converts fine. TOML doesn't support null values directly — they may be omitted or cause errors.
What are common TOML file types?
Cargo.toml (Rust), pyproject.toml (Python), hugo.toml (Hugo sites), mise.toml (dev environment), and many CLI tool configs.
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