JSON → TOML

Turn JSON into readable TOML: tables, arrays-of-tables, and all.

Your data is processed entirely in your browser and is never uploaded.

Tool workspace

INPUT JSON

Drag & drop file here or browse

Status: Empty0 chars

Options

Null values

TOML has no null. Refuse is the honest default; strip removes them.

Ready, paste to start
OUTPUT TOML
Output: Empty0 chars
HOW IT WORKS

Convert JSON in three steps

Paste or drop

Any JSON object. Validity reads as you type, up to 15M characters.

Convert

Press Convert (or Ctrl/⌘ + Enter). Big files run in a background worker.

Take the TOML

Copy or download the result. Objects become [tables]; arrays of objects become [[arrays.of.tables]].

Docs · Convert

Translating JSON into a config format with no null

JSON → TOML parses a JSON object and writes it back as TOML: objects become [tables], arrays of objects become [[arrays.of.tables]], and scalars keep their types. The one real friction is null. TOML has no null value, so by default the converter refuses and points at the exact path (like limits.timeout or tools[2]); switch to "Strip nulls" to drop those keys/elements and convert anyway. A top-level JSON array fails too, because TOML's root must be a table. Large files run in a background worker, and the output is clean, hand-editable TOML.

Common issues & tips

TOML has no null

A JSON null has nowhere to live in TOML. The converter refuses by default and names the exact path; switch to "Strip nulls" to drop those keys and convert anyway.

{"limits": {"timeout": null, "retries": 3}}
A top-level array has no home

TOML's root must be a table (an object). A top-level JSON array, or a bare string, number, or boolean, has nowhere to live. The converter explains that instead of wrapping it in a made-up key.

[{"name": "Ada"}, {"name": "Alan"}]
Numbers keep their shape

JSON's single number type maps to TOML integers and floats. Very large integers (beyond 2^53) can lose precision. That's a JSON limit, not a bug here.

Objects become tables

A nested object becomes a [table]; an array of objects becomes an [[array.of.tables]]. Plain arrays of scalars become inline arrays, and order is preserved.

{"servers": [{"host": "a", "port": 80}, {"host": "b", "port": 443}]}

Try these

Simple object
{"name": "Ada", "role": "engineer", "level": 7}

Flat keys map straight to TOML.

Nested tables
{"database": {"host": "localhost", "ports": [5432, 5433]}}

Objects become [tables]; nested values stay grouped.

Array of tables
{"servers": [{"host": "a", "active": true}, {"host": "b", "active": false}]}

An array of objects becomes [[arrays.of.tables]].

pair this withReverse it → TOML → JSON·Validate the source → JSON Validator·Or convert to YAML → JSON → YAML

compare
TOML → JSON vs JSON → TOML
Related

Where to next

Reverse it
TOML → JSON

Convert TOML configs into JSON.

Open Validate the source
JSON Validator

Check JSON syntax and pinpoint the exact error line.

Open Or convert to YAML
JSON → YAML

Turn JSON into readable YAML.

Open
FAQ

Frequently asked questions

Is my JSON uploaded anywhere?

No. Conversion runs entirely in your browser (in a background worker for large files). Your data never leaves your machine.

Why does a top-level array fail?

TOML's root must be a table (an object). A top-level JSON array, or a bare string, number, or boolean, has nowhere to live, so we explain that instead of silently wrapping it in a made-up key.

What happens to null?

TOML has no null value. By default we refuse and point at the exact path (likelimits.timeout or tools[2]); switch to "Strip nulls" to drop those keys/elements and convert anyway.

Do numbers stay exact?

JSON's single number type maps to TOML integers and floats. Very large integers (beyond 253) can lose precision. That's a JSON limit, not a bug here.