TOML ⇄ JSON Converter

Convert between TOML and JSON with validation and formatting. Free online config converter for developers.

JSON indent:

Input TOML

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Converted JSON

Bidirectional conversion

Convert between TOML and JSON with validation and error handling. Ideal for Cargo, pyproject.toml, and CI configs.

Real-time validation

Instant validation with detailed error messages for both TOML and JSON.

File support

Upload .toml or .json files and download converted output. No sign-up required.

TOML ⇄ JSON Converter

TOML (Tom's Obvious, Minimal Language) and JSON are widely used for configuration and data. This free converter lets you switch between them with validation and formatting. Perfect for Rust Cargo.toml, Python pyproject.toml, and CI configs.

Key features

Bidirectional conversion: TOML to JSON and JSON to TOML with one click, preserving structure and types.
Validation: Instant syntax checking and clear error messages for both formats.
JSON indent: Choose 2, 4, or 8 spaces for JSON output.
File support: Upload .toml or .json and download the converted result.
Copy and sample: One-click copy and sample data to get started quickly.

Common use cases

Rust / Cargo: Convert Cargo.toml to JSON for tooling or inspection.
Python: Work with pyproject.toml and JSON configs in one place.
CI/CD: Transform configs between TOML and JSON for different systems.
APIs and tooling: Use JSON where TOML is not supported.

Why use this tool

Runs in your browser; no data is sent to a server.
Free and no sign-up required.
Works on desktop and mobile.