JSON to TOML Converter

The JSON is checked first, and an error names the line and column. Then each nested object becomes a table ([server]), nested deeper as [server.tls], and an array of objects becomes an array of tables ([[workers]]). Plain values are written before the tables of the same object, as TOML requires, so the order of keys can change. Keys that are not bare keys are quoted: "key with space". Arrays may mix types, which TOML allows since version 1.0.

Some JSON cannot be written as TOML. A TOML document is a table, so the top-level value must be an object: an array or a string gives an error that says so. TOML has no null: by default the tool stops and names the path of the value, such as $.database.password, or you can choose to leave those keys out. Whole numbers are written as integers and numbers with a fraction as floats, and integers beyond 2⁵³ are written as floats because they cannot be exact.

With Date strings → TOML dates, strings that are valid RFC 3339 values are written as TOML dates without quotes: 2026-09-28T17:42:09Z (offset date-time), 2026-09-28T17:42:09 (local date-time), 2026-09-28 (local date) and 17:42:09 (local time). Turn the option off to keep them as strings. The conversion uses smol-toml and runs in your browser.