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JSON to TOML
Turn a JSON object into a TOML document with proper tables and arrays of tables.
Quick Tool Overview
The JSON to TOML converter writes nested objects as [table] headers and arrays of objects as [[table]] blocks, with every scalar key placed above the first header beneath it so the scoping is correct.
- What it does
- Converts a JSON object into a TOML document
- You give it
- A JSON object — TOML documents are tables
- You get back
- TOML with proper tables and arrays of tables
- Best for
- Writing Cargo, Python packaging and site configs
About the JSON to TOML
TOML is what Rust, Python packaging and a growing number of tools expect for configuration, and hand-translating a JSON config into it is fiddly. This converter does the structural work: nested objects become [table] headers, arrays of objects become [[table]] blocks.
The ordering rule is applied automatically. Every scalar key in a section is written before the first table header beneath it, because TOML would otherwise read it as belonging to that table. Strings are quoted and escaped, multi-line strings use the triple-quote form, arrays of scalars stay inline, and keys that are not bare-safe get quoted. The root must be an object, since a TOML document is a table.
Key features of the JSON to TOML
Correct key ordering
Scalars are written before the first table header in their section, because TOML would otherwise read them as part of that table.
Arrays of tables
A list of objects becomes a repeated [[header]] block, which is the only TOML form for structured entries.
Inline where it reads better
Arrays of scalars stay on one line rather than being expanded into something harder to read.
Keys quoted when needed
A key that is not bare-safe is quoted automatically, so the output always parses.
Multi-line strings
A value containing line breaks uses the triple-quote form instead of a wall of escape sequences.
How to use the JSON to TOML
-
1
Paste your JSON
The root must be an object — a TOML document is a table.
-
2
Review the tables
Nested objects become [headers] and arrays of objects become [[headers]].
-
3
Check the ordering
Plain keys are written above the first table header, as TOML requires.
-
4
Copy the TOML
Ready to paste into Cargo.toml, pyproject.toml or your own config.
Frequently asked questions
A TOML document is a table by definition, so there is nowhere for a bare array or string to live at the top level. Wrap the value in an object with a named key.
As an array of tables: the [[header]] is repeated once per element. That is the only TOML form for a list of structured entries.
TOML has no null. Nulls become empty strings, which is the closest equivalent — so remove the key entirely if "absent" is what you mean.
Yes. Each level adds a dotted segment to the table header, so a.b.c becomes [a.b.c].
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