Convert TOML to JSON Online

Convert TOML configuration files to JSON format. Handles Cargo.toml, pyproject.toml, Hugo configs, and any TOML document with full spec compliance.

Converter

TML

TOML <-> JSON Converter

Convert between TOML and JSON formats instantly

Direction

Indent

Validate only

Input

Output

Share to Community

Quick Start

1Paste your TOML content into the input editor
2JSON output appears automatically
3Review the converted JSON structure
4Copy or download the JSON result

What This Tool Does

TOML is read by a full parser rather than a set of pattern matches, so tables, arrays of tables, dotted keys, inline tables, multi-line strings and every numeric form (hex, octal, binary, exponents and underscore separators) come through with their real types.

Dates are where TOML and JSON stop agreeing. An offset date-time carries a timezone and is written out as an ISO 8601 string. A local date, local time or local date-time has no offset, so it is kept exactly as written instead of being pushed into UTC and silently shifting by a few hours.

Validate only is worth using on its own. It parses without producing output and tells you whether the document is valid, which is a quick way to check a Cargo.toml or a pyproject.toml before you commit it.

Limits Worth Knowing

Input is capped at two megabytes, because the whole parse runs on your own machine.
Comments are not carried into the JSON. TOML files tend to be heavily commented, so keep the original.
A duplicate key, or a table declared twice, is a hard error with a line and column rather than a last-one-wins merge.
Going the other way, a JSON null becomes an empty string, because TOML has no null value.
Output indentation is two spaces, four spaces, a tab, or minified onto a single line.

Common Questions

Does it handle arrays of tables?

Yes. A repeated double-bracket section header becomes a JSON array of objects, including when those sections are nested inside another table.

Why is my date still a string?

Only date-times carrying a UTC marker or an offset are converted. A bare date or time has no timezone, so converting it would mean inventing one, and the original text is kept instead.

Can I convert JSON back to TOML?

Yes, as long as the top level is an object. TOML has no way to represent a bare array or a single scalar as a whole document, so those are rejected.

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Looking for FAQs and advanced options? Visit the full TOML/JSON Converter page →