JSON to TOML Converter

How to use

1. 1Paste your JSON into the input area on the left. Click Load sample for a worked TOML-style example, or start with your own object.
2. 2Pick a Tables style: Section tables for [a.b] headers (the standard TOML look) or Inline tables to keep nested objects on one line.
3. 3Pick how Arrays of objects render: [[arrays of tables]] for a clean per-record block, or Inline arrays to keep them as one [ { ... }, { ... } ] list.
4. 4Pick whether ISO-8601 date strings should print as native TOML date-time literals (unquoted) or as quoted strings. Pick a JSON null policy: skip and annotate, or error.
5. 5Copy the TOML output or download it as a .toml file. Use the JSON-to-X siblings (YAML, XML, CSV) if you need a different target format.

About this tool

JSON to TOML Converter turns any JSON value into a TOML v1.0 document right in your browser. The serializer covers every part of the spec that has a clean mapping from JSON: section tables for nested objects ([a.b]), inline tables for compact one-line objects ({ a = 1, b = "x" }), arrays of tables for arrays of objects ([[products]]), inline arrays for arrays of scalars or mixed types, basic strings with the standard \b \t \n \f \r \" \\ \uXXXX escapes, multi-line basic strings for any value containing a newline, integers (with safe-integer detection that promotes very large integers to floats so no precision is lost), floats (including NaN, +Infinity, and -Infinity, which TOML writes as nan, inf, and -inf), and booleans. Keys made of letters, digits, underscores, and hyphens are emitted bare; everything else is automatically quoted using TOML's basic-string rules. ISO-8601 / RFC 3339 date-time strings (offset date-times like 1979-05-27T07:32:00-08:00, local date-times, local dates, and local times) can optionally be unquoted so they print as TOML date-time literals, matching how Cargo, pyproject, Hugo, and Netlify configs prefer to express timestamps. The output offers two table styles. Section tables put every nested object under its own [a.b] header, which is the readable default for hand-edited configs. Inline tables keep nesting on one line, which is closer to the structure of the source JSON and is easier to grep. Arrays of objects can either become [[arrays of tables]] blocks (auto mode) or stay as inline arrays ([{ ... }, { ... }]). JSON has a null literal that TOML does not, so the converter offers two policies for handling them: skip drops the entry and writes a # comment in its place noting that TOML has no null type; error fails the conversion so you can change the source instead of silently losing data. A summary panel above the output shows the line count, key count, table count, byte size, and how many null values were skipped during the run, with a copy and a download button so you can drop the result straight into a Cargo.toml, pyproject.toml, hugo.toml, netlify.toml, or any custom configuration file. Conversion runs entirely in your browser using JSON.parse and a small dependency-free emitter; the JSON you paste here is never uploaded, logged, or sent to any server.

Free to use. Works in your browser. No signup, no login.