JSON to TOML Converter
JSON → TOML v1.0.0 via @iarna/toml. Nested objects become tables, object arrays become arrays of tables ([[bin]]).
JSON to TOML Converter — Free Online Tool
Converts JSON documents into TOML v1.0.0 using @iarna/toml, turning nested objects into tables and arrays of objects into arrays of tables ([[bin]]), while reporting the null values that TOML cannot represent, useful for migrating package manifests and service configs from JSON to Cargo.toml, pyproject.toml and Netlify or Hugo configuration.
How to use the JSON to TOML Converter
- Open the tool above — it runs entirely in your browser, so your input never leaves this page.
- Paste or type your input into the field, then press the relevant button (e.g. Encode / Decode, Generate, or Convert).
- Copy the result from the output area with the copy button orCtrl/Cmd + C.
- No signup, no upload, and no tracking — repeat as often as you need.
Frequently asked questions
Why are my null values missing from the TOML output?
TOML v1.0.0 has no null type. Keys whose value is null are dropped and the tool reports how many were removed — if the key matters, give it an explicit default (an empty string, 0, or false) in the JSON before converting.
Why does it reject a JSON array at the top level?
A TOML document is always a table at the root, so [1, 2, 3] or a bare string has nowhere to live. Wrap the array in an object, for example {"items": [...]}, and it becomes a valid TOML key with an array value.
How are arrays of objects converted?
An array of objects becomes an array of tables — each element is emitted as its own [[key]] block. That is why a JSON "bin": [{...}, {...}] turns into two [[bin]] sections in Cargo.toml style.
Free & private — why use this JSON to TOML Converter
The JSON to TOML Converter runs 100% client-side in your browser. Your data is never uploaded to a server, no account is required, and the tool is completely free. It works offline once the page has loaded and is part of a growing collection of privacy-first developer utilities.