TOML to JSON Converter Online — JSON to TOML Tool
TOML Converter
Convert between TOML and JSON. Auto-detects direction from input format.
Free online TOML ↔ JSON converter. Paste TOML configuration to get JSON output, or paste a JSON object to get TOML format. Auto-detects the input format and converts in the right direction. Supports the full TOML v1.0.0 spec including sections, arrays of tables, inline tables, and all TOML data types. Perfect for Rust developers (Cargo.toml), Python (pyproject.toml), and Hugo/Zola static site configurations. Runs entirely in your browser.
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Tags: toml, json, converter, config, rust, cargo, pyproject
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How to TOML Converter Online
Choose the conversion direction: JSON to TOML or TOML to JSON.
Paste your input into the input area on the left.
Click Convert or press ⌘↵ (Mac) / Ctrl+Enter (Windows) to convert.
Copy the output or download it as a .toml or .json file.
TOML Converter Features
Converts JSON to TOML and TOML back to JSON.
Supports nested objects, arrays of tables, and inline tables.
TOML output is formatted for readability with section headers for nested objects.
Validates input before conversion and reports parse errors with clear messages.
Works entirely in your browser — data never leaves your device.
Keyboard shortcut ⌘↵ for instant conversion.
Frequently Asked Questions
- What is TOML?
- TOML (Tom's Obvious, Minimal Language) is a configuration file format designed to be easy to read. It uses a simple key = value syntax with sections ([table]) for nesting. TOML is widely used for Rust (Cargo.toml), Python (pyproject.toml), and Hugo configuration files.
- When should I use TOML instead of JSON for configuration?
- TOML is more human-readable than JSON for configuration files: it supports comments, multiline strings, and a cleaner syntax without all the quotes. JSON is better for data interchange because it is universally supported. Use TOML for config files that humans edit, and JSON for API payloads.
- Can TOML represent everything JSON can?
- Almost. TOML supports strings, integers, floats, booleans, dates, arrays, and tables. It cannot natively represent null values (JSON null has no TOML equivalent), and mixed-type arrays have limited support. Simple nested objects and arrays convert cleanly in both directions.
- Is my data safe?
- All conversion runs in your browser using pure JavaScript (via the smol-toml library). No data is ever sent to a server. Your content stays completely private.
- What is pyproject.toml?
- pyproject.toml is the standard configuration file for Python projects, defined in PEP 518. It uses TOML to specify build system requirements, project metadata, and tool configuration (e.g. for Poetry, Hatch, or Ruff). You can paste its contents into this tool to convert it to JSON for inspection.
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