Format converter
JSON ↔ TOML, spec-compliant.
Convert a JSON object into the TOML config format used by Cargo, pyproject, Hugo, and many CLI tools — or paste TOML and pull out a clean JSON tree.
Runs entirely in your browser
Spec-compliant
Powered by @iarna/toml, the most-used JS TOML parser. Tables, arrays-of-tables, inline tables, date types — all supported.
Predictable output
Object keys become TOML sections; nested objects flow into [a.b.c] tables; arrays of objects become [[a.b]] entries.
Lossless round-trip
TOML → JSON → TOML preserves the meaningful structure (key order is not preserved per TOML spec).
Privacy-first
All conversion runs locally — your config never leaves the browser. Ideal for files that contain secrets.
FAQ
Will my Cargo.toml round-trip?
Yes for the standard tables / dependencies / metadata. Comments are stripped during JSON serialization (TOML's comment model has no JSON equivalent).
What about dates?
TOML date and date-time types map to JSON ISO 8601 strings during conversion, and the library re-parses them on the way back.
Does the input need an object at the root?
Yes — TOML only models top-level tables. Arrays-at-root are rejected with a clear error.