Why must JSON have a top-level object to become TOML?

TOML files are always a table of key/value pairs at the root, so a top-level array or primitive has no valid TOML representation. Wrap such data in an object first.

Does it preserve data types?

Yes. Numbers, booleans, strings, dates, arrays, and nested tables are mapped to the matching type in the target format, so the converted output is faithful to the original.

What is TOML used for?

TOML (Tom's Obvious, Minimal Language) is a configuration format designed to be easy for humans to read and write. It is widely used by Rust's Cargo, Python packaging (pyproject.toml), and many other developer tools.

Why can't I convert a JSON array to TOML?

A TOML document must be a table of key/value pairs at its root, so a top-level array or single value has no valid representation. Wrap the data in an object with a key first, then convert.

Are comments preserved?

No. Comments are not part of the data model, so converting strips them. The converter translates the structured values, not the surrounding annotations.

Does it handle nested tables and arrays of tables?

Yes. Nested TOML tables become nested JSON objects and back again, and arrays of tables are mapped to arrays of objects, so complex configs round-trip correctly.

TOML ↔ JSON Converter

Translate config files both ways between TOML and JSON with a real TOML parser, getting clean, correctly typed output and clear error messages when the input is malformed — all processed locally.

Updated June 2026

Files never leave your browser

Input TOML

Output JSON

Conversion runs entirely in your browser — your data is never uploaded.

How to use TOML ↔ JSON Converter

TOML and JSON are two popular formats for configuration files, and this converter translates between them in both directions. Paste a TOML config to get clean, formatted JSON, or paste JSON to produce equivalent TOML. It uses a real TOML parser so types are preserved correctly — numbers stay numbers, booleans stay booleans, dates stay dates, and nested tables map to nested objects. When the input is malformed, you get a clear error instead of broken output. Everything runs in your browser, making it a fast, private way to move config between tools that expect different formats.

Choose the direction: TOML to JSON or JSON to TOML.
Paste your config into the input box.
Read the converted output on the right.
Fix any reported errors in the source.
Copy the result into your target file.

Your data never leaves your device — 100% private processing.

TOML and JSON compared

JSON is the lingua franca of data interchange — compact, ubiquitous, and supported everywhere — but it was designed for machines and is awkward to write by hand, with no comments and fussy punctuation. TOML was created to fix exactly that for configuration: it reads almost like an INI file, supports comments, and has unambiguous, human-friendly syntax for dates, multi-line strings, and nested sections. Many tools accept one format but not the other, which is where conversion comes in. Translating TOML to JSON lets you feed a hand-written config into code or APIs that speak JSON, while converting JSON to TOML produces a version that is pleasant for people to edit.

How types are mapped

Faithful conversion depends on preserving types, and this tool relies on a proper TOML parser rather than naive string manipulation to do that. TOML integers and floats become JSON numbers; booleans map directly; basic and literal strings become JSON strings; arrays become arrays; and tables and inline tables become objects. TOML's native date and time values are converted to ISO-style strings in JSON, since JSON has no date type of its own. Going the other way, the parser inspects each JSON value and emits the matching TOML syntax. Because the mapping is type-aware, a config converted from TOML to JSON and back arrives essentially unchanged apart from comments and incidental whitespace.

Worked examples

TOML → JSON

Inputs: name = "app" [db] host = "local"

Result: { "name": "app", "db": { "host": "local" } }

JSON → TOML

Inputs: { "port": 8080 }

Result: port = 8080

Glossary

TOML: A minimal, human-friendly configuration file format.
JSON: A widely used data-interchange format based on objects and arrays.
Table: A TOML key/value grouping, equivalent to a JSON object.
Array of tables: A TOML construct that maps to a JSON array of objects.

Frequently Asked Questions

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Why use TOML ↔ JSON Converter?

Converts in both directions: TOML to JSON and JSON to TOML
Preserves data types including numbers, booleans, dates, and nested tables
Gives clear error messages for malformed input
Runs entirely in your browser, so your config is never uploaded

Common use cases

Convert a Rust or Python TOML config to JSON for a script
Turn a JSON settings file into TOML for a tool that requires it
Inspect a TOML file as JSON to understand its structure
Migrate configuration between tools with different format needs
Validate that a TOML file parses correctly

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