About this tool
TOML (Tom's Obvious, Minimal Language) is a configuration format designed to be easy to read, with clear sections and typed values. JSON is the lingua franca of APIs and tooling. This converter parses TOML into the equivalent JSON object — tables become nested objects, arrays of tables become arrays — and converts JSON back into valid TOML.
Paste TOML or JSON, pick the direction, and the result appears formatted and ready to copy. The input is validated, so a syntax error is reported rather than producing a broken result. Because TOML's root is always a table, converting JSON to TOML requires a top-level object.
Conversion runs entirely in your browser — your config never leaves your machine.
Frequently asked questions
Is the conversion lossless?
For data both formats support, yes. TOML has no null type, so JSON nulls can't be represented in TOML; dates and times use TOML's native datetime types. Tables map to objects and arrays-of-tables to arrays.
Why does JSON → TOML need a top-level object?
TOML documents are always a table at the root, so the top-level JSON value must be an object. A bare array or scalar can't be expressed as a TOML document — wrap it in an object first.
What about Cargo.toml or pyproject.toml?
Both are standard TOML and convert cleanly to JSON for inspection or programmatic editing, then back to TOML.