What is the difference between TOML and JSON?

TOML (Tom's Obvious Minimal Language) is a configuration format designed to be easy for humans to read and write, with named tables, comments and first-class date types. JSON (JavaScript Object Notation) is a stricter data-interchange format with no comments and only string, number, boolean, null, array and object types. This converter maps cleanly between the two so you can edit in whichever format suits the tool you are feeding.

Does it support the full TOML 1.0.0 specification?

Yes. It uses a complete TOML 1.0.0 parser, so multi-line basic and literal strings, inline tables, arrays of tables, dotted keys, and hex, octal and binary integers all parse correctly — not just simple key/value pairs.

What happens to TOML dates and times when I convert to JSON?

JSON has no date type, so offset date-times, local date-times, dates and times are rendered as ISO-8601 strings (for example 2026-05-30T09:00:00.000Z). The value is preserved as readable text rather than being lost.

Why was my JSON null dropped when converting to TOML?

TOML has no null type by design. When you convert JSON to TOML, any null values are removed and a warning is shown, because there is no valid way to represent null in a TOML document. Replace the null with a sentinel value or an empty string first if you need to keep the key.

Can I convert a top-level JSON array to TOML?

No — a TOML document must be a table (object) at the top level, so a bare array or scalar is not a valid TOML document. Wrap your array inside an object key, such as {"items": [ ... ]}, and the converter will produce valid TOML.

Is my data sent to a server?

No. Parsing, validation and conversion all happen locally in your browser using JavaScript. Nothing you paste is uploaded, logged or stored anywhere except your own browser, which remembers your last input so you can pick up where you left off.

TOML ⇄ JSON Converter

A two-way TOML ⇄ JSON converter that turns one format into the other the moment you paste it. It is built for developers wrangling configuration files — moving a Cargo.toml, pyproject.toml, netlify.toml or any hand-written config into JSON for a script or an API, and back again for a human to edit. Paste either format on the left and the converted result appears live on the right, ready to copy or download.

How it works

The converter runs a full TOML 1.0.0 parser entirely in your browser, so it handles far more than basic key/value pairs: named [tables], [[arrays of tables]], inline tables, dotted keys, multi-line basic and literal strings, and integers written in hex, octal or binary. When you paste, the tool inspects the text — anything that begins with { or [ and parses as valid JSON is treated as JSON; everything else is treated as TOML. You can override that guess at any time with the direction dropdown.

Because the two formats do not have identical type systems, the converter bridges the gaps explicitly rather than silently corrupting data. TOML’s date and time values become ISO-8601 strings in JSON. Very large TOML integers, which exceed JavaScript’s safe number range, are emitted as strings so no precision is lost. Going the other way, JSON null has no TOML equivalent, so null values are stripped and a clear warning is shown. If you paste invalid TOML, the error message points at the exact line and column so you can find the typo fast. You can choose 2-space, 4-space or tab indentation for the JSON output, and the Use as input button feeds the result straight back in so you can round-trip a file and confirm it survives the trip unchanged.

Example

Paste this TOML:

title = "Gera Tools" followed by a [owner] table with team = "platform", and the tool returns the equivalent JSON object { "title": "Gera Tools", "owner": { "team": "platform" } }. Switch the dropdown to JSON → TOML, paste that object back, and you get the original TOML structure again — tables, arrays and all. The table below shows how common values map across the two formats.

Concept	TOML	JSON
String	`name = "eu-1"`	`"name": "eu-1"`
Integer	`port = 8080`	`"port": 8080`
Boolean	`active = true`	`"active": true`
Array	`ports = [8080, 8081]`	`"ports": [8080, 8081]`
Table	`[owner]`	`"owner": { ... }`
Date	`launched = 2026-05-30T09:00:00Z`	`"launched": "2026-05-30T09:00:00.000Z"`

Everything is processed locally in your browser — no file you paste is ever uploaded or stored on a server.